GeForce Experience doesn’t recognize game, how to add it manually?

I’ve been playing FiveM for a while but I’ve always had some performance issues there. I don’t know why, but GTA keeps using more of my CPU than my GPU. People told me that’s not normal and that I should try to optimize it.

I went to check GeForce Experience, and GTA V shows up there, but not FiveM. Is there a way to add it manually? If so, how?