Need help applying force to objects hit by raycast

Hi, I have this gun script which uses a raycast to hit and damage an enemy. How would I go about adding force upon the hit so that the enemy is knocked back (sort of like when gun impacts in movies are exaggerated and a person flies back upon being hit)? Also I would like to be able to do the same with static gameobjects in the world (in boxes move when shot etc).

Here is my gun code (I know its quite poorly coded and the reload doesn't add up right, but I'm learning trying to piece bits together). Also if anyone has any suggestions how to fix the KickBack function that would be great, its meant to make the gun move when fired like recoil, but it only moves the gun once and doesn't return to its original position.

 using UnityEngine;
 using System.Collections;
 
 public class PerformsAttack : MonoBehaviour {
 
     public float cooldown = 0.2f;
     float cooldownRemaining = 0;
     public float range = 100.0f;
     public GameObject bulletSpwan;
 
     public GameObject projectilePrefab;
 
     public GameObject debrisPrefab;
 
     public float damage = 50f;
 
     public GameObject mainCamera;
     public GameObject weaponCamera;
     public int FOV = 40;
     public float zoomSpeed = 0.5f;
     
     public float bullets = 5.0f;
     public float ammoClip = 5.0f;
     public float maxClips = 3.0f;
 
     private bool aiming = false;
 
     public AudioClip gunshot;
     public AudioClip reload;
 
     private Vector3 curVect;
     public Vector3 aimPosition;
     public float aimSpeed = 0.25f;
     public Vector3 hipPosition;
     public float maxInaccuracyHIP = 5.0f;
     public float maxInaccuracyAIM = 1.0f;
     private float baseInaccuracy;
     public float baseInaccuracyAIM = 0.005f;
     public float baseInaccuracyHIP = 1.5f;
     private float maximumInaccuracy;
 
     public Transform kickGO;
     public float kickUpside = 0.5f;
     public float kickSideways = 0.5f;
 
 
     // Use this for initialization
     void Start () {
         weaponCamera = GameObject.FindWithTag("WeaponCamera");
         mainCamera = GameObject.FindWithTag("MainCamera");
         GetComponent<AudioSource> ();
     }
     
     // Update is called once per frame
     void Update () {
         cooldownRemaining -= Time.deltaTime;
 
         if (Input.GetButton ("Fire1") && cooldownRemaining <=0 && bullets >= 1) {
             Shooting ();
         }
 
         if (Input.GetButtonDown ("Reload")){
             Reload ();
         }
 
         if (Input.GetButton("Fire2"))
         {
             if (!aiming)
             {
                 aiming = true;
                 curVect = aimPosition - transform.localPosition;
             }
             if (transform.localPosition != aimPosition && aiming)
             {
                 if (Mathf.Abs(Vector3.Distance(transform.localPosition, aimPosition)) < curVect.magnitude / aimSpeed * Time.deltaTime)
                 {
                     transform.localPosition = aimPosition;
                 }
                 else
                 {
                     transform.localPosition += curVect / aimSpeed * Time.deltaTime;
                 }
             }
         }
         else
         {
             if (aiming)
             {
                 aiming = false;
                 curVect = hipPosition - transform.localPosition;
 
             }
             
             if (Mathf.Abs(Vector3.Distance(transform.localPosition, hipPosition)) < curVect.magnitude / aimSpeed * Time.deltaTime)
             {
                 transform.localPosition = hipPosition;
             }
             else
             {
                 transform.localPosition += curVect / aimSpeed * Time.deltaTime;
             }
         }
         
         if (aiming)
         {
             maximumInaccuracy = maxInaccuracyAIM;
             baseInaccuracy = baseInaccuracyAIM;
             mainCamera.GetComponent<Camera>().fieldOfView -= FOV * Time.deltaTime / zoomSpeed;
             if (mainCamera.GetComponent<Camera>().fieldOfView < FOV)
             {
                 mainCamera.GetComponent<Camera>().fieldOfView = FOV;
             }
             weaponCamera.GetComponent<Camera>().fieldOfView -= 40 * Time.deltaTime / zoomSpeed;
             if (weaponCamera.GetComponent<Camera>().fieldOfView < 40)
             {
                 weaponCamera.GetComponent<Camera>().fieldOfView = 40;
             }
         }
         else
         {
             maximumInaccuracy = maxInaccuracyHIP;
             baseInaccuracy = baseInaccuracyHIP;
             mainCamera.GetComponent<Camera>().fieldOfView += 60 * Time.deltaTime / 0.5f;
             if (mainCamera.GetComponent<Camera>().fieldOfView > 60)
             {
                 mainCamera.GetComponent<Camera>().fieldOfView = 60;
             }
             weaponCamera.GetComponent<Camera>().fieldOfView += 50 * Time.deltaTime / 0.5f;
             if (weaponCamera.GetComponent<Camera>().fieldOfView > 50)
             {
                 weaponCamera.GetComponent<Camera>().fieldOfView = 50;
             }
         }
     }
 
     //Fire weapon
     void Shooting () {
         cooldownRemaining = cooldown;
         bullets -= 1;
         GetComponent<AudioSource>().PlayOneShot (gunshot);
 
         Ray ray = new Ray (bulletSpwan.transform.position, bulletSpwan.transform.forward);
         RaycastHit hitInfo;
         
         if (Physics.Raycast (ray, out hitInfo, range)) {
             Vector3 hitPoint = hitInfo.point;
             GameObject go = hitInfo.collider.gameObject;
             Debug.Log ("Hit Point: " + hitPoint);
             
             //Health h = go.GetComponent<Health>();
             EnemyControllerTest h = go.GetComponent<EnemyControllerTest> ();
             
             if (h != null) {
                 h.RecieveDamage (damage);
             }
             
             if (debrisPrefab != null) {
                 Instantiate (debrisPrefab, hitPoint, Quaternion.identity);
             }
 
             if (bullets == 0) {
                 Reload ();
             }
 
         }
 
         KickBack ();
     }
 
     void OnGUI() {
         if (GUI.Button (new Rect (10, 10, 90, 25), "Bullets : " + bullets)){}
         
     }
 
         void Reload () {
 
         GetComponent<AudioSource>().PlayOneShot (reload);
         if (maxClips >= 1) {
         
             bullets = ammoClip;
             maxClips -= 1;
         }
 
     }
 
     void KickBack()
     {
         kickGO.localRotation = Quaternion.Euler(kickGO.localRotation.eulerAngles - new Vector3(kickUpside, Random.Range(-kickSideways, kickSideways), 0));
     }
 
 
 }