If your talking about sealing the bolts that go into the roof, regular RTV works. I had a half tube left over from a valve cover project or something and used a dab on the upper threads. Four years later, I needed to remove some of the screws and they were fine. I spent a few decades working for GM, black RTV is what we used on screws that didn't have a seal.
If you have new bolts and their stainless, put a small amount of anti-seize on the lower threads and sealant on the top threads and under the bolt head. If you do it right, you dont have to wipe much off after your done.
There's better sealants out there but be careful, you may need to remove the bolts one day.
EDIT: Pictures or it doesn't exist.
