I was able to put this rounded frame on the top left of the screen to cover the TopBar buttons since I made the TopBar Transparent, and it was easy because I know each button is 50 (X) and 36 (Y). Like this: 
Now I’m trying to do the exact same thing on the top right side, covering the playerlist. Any tips on how?
The Y should still remain 36. Are you using offset entirely?
Yea I’m using offset entirely. I know 36 is the Y but I need the X.
Trial and error should get you there quite fast, if it’s a case of pure offset.
Wait, shouldn’t this be in Art Design Support instead? Since this doesn’t seem to have anything to do with scripting.
Agreed. If you do a bit of T&E, you should find a value that fits. It’s up to you 
Should be 170 in length. I just tried for myself in Studio.
The minimum size of the playerlist is 165 on offset and scales based on circumstances. I would advise that you take a look through the CoreScripts and check out player sizing rather than “trial and error”.