Dicor self leveling Lap Sealant is the product to use for your application.
The above posters are all correct in that you should not use a silicon product on the rubber roof.
If it were my RV, I would use
Eternabond Tape around the vents and any other seams on the roof. I did this on our RV about 9 years ago and it still is holding and looks like new. Many others here report the same results. It is a permanent fix for most applications.
If you are looking for a short, temporary repair then the Dicor caulk would be the answer.
Barney
