Yeah if they are for RocketLauncher then they wont work with MAME. The bezels i have are on the emumovies ftp if you have access to that, i think the same ones are also posted in letter packs here on our forums.
https://forums.launchbox-app.com/files/category/12-platform-bezelsoverlays/
As for sizes of the game screen, that can be adjusted inside the actual zip files, its not something i have ever done though and you would have to do it for every zip. Most have several views though, just use one that doesnt have the fake monitor bezel on it.