How to display a camera on the screen while displaying the Oculus Rift in direct mode ?

Hi everybody !

I want to create a local multiplayer gameplay that include one player using the oculus rift and another one using the computer. I already implemented the differents gameplay for both of them individualy. I already stop the mirroring of the Oculus using :
VRSettings.showDeviceView = false;

And now I want to know, how to display my regular Camera on the monitor screen ?
Is there a solution with the wiewport, a RenderTexture, the targetDisplay parameter of the camera or something else ?

I read topics about "-popupwindows" but I didn't understand anything. If it's the viable solution please explain it with some examples.
Thank you.