From Andy at Inland RV
Here are the instructions per Andy, I don't know how to link his thread so I just copied it:
"The three drill bit sizes that you will need are #30, 21 and 11.
We have a drill bit assortment kit available.
Olympic rivets are used on the exterior, unless you have a portion of the interior off. You then could use "buck" rivets.
The underbelly uses 3/16" pop rivets.
Drilling out the original buck rivets takes a # 30 drill bit. The holes are then opened up with a # 21 drill bit for the olympic rivets. "DO NOT" drill out the od original rivets with a # 21. The idea is that you can and will have oval holes with the #30 drill bit, since you cannot absolutely center the drill bit. Those holes are trued back to round with the second drilling, using a #21. If you attempt to drill out the old rivets with a #21, again you will have oval holes. The problem then is that you would have to true the hole with a #11and the use an oversize 3/16 rivet. Olympics are not available in 3/16, and if they were, the rivet head would be much larger than the buck rivet heads.
Also you will need a "shaver" if your going to do a bunch of rivets. If not, then you can dress then down with a Dremel tool, but they will all have a different appearance from each other.
You should use "vulkem" sealer when replacing rivets and/or sheet metal."