YES! But with a added note that it probably doesn't help to check for leaks!
When you look at using it to check for roof leaks, keep in mind that you are trying to put pressure in what is almost like a sieve and you have to put a very large amount of air in to build any worthwhile pressure.
Depending on the Rv, some places to think about leaks:
Any vents, windows are often sliders which hold out water but are pretty much open, lots of Rv doors could let a cat out, Speakers are just a piece of paper between inside and the body parts that are not sealed, the plumbing drains and pipes often go to the storage through holes that are not fully sealed.
Like blowing up a broken balloon, you would have to put more air in than was leaking out?
2015 Winnebago Vista 31KE on 2014 chassis