Good question, I spent alot of time trying to get the hole for the reese rivet nut as snug as possible. Then found it wasn't that important.
Once the hole is drilled, place the bracket over the rivet nut and use a C Clamp to put pressure on bracket and thereby clamping the rivet nut edge to keep it from spinning while you tighten it as it expands inside the frame. After several turns, you will feel it get tighter when the internal expansion is complete.
******************************************************************
Another tip is to use a step drill to drill the hole in the frame, it will keep the hole nice and clean.
******************************************************************
If you use the drill bits reese recommends, you might have trouble with the drill bit catching on the edge. These tips were given to me by a friend who owns a machine shop and they were very helpful.
