Originally Posted by JonM
5/64 or 1/16 will do it. helps to preserve the roll pin if you use a roll pin punch instead of a flat punch
Also helps if you use another punch to align the holes and knock it out of the way when you hammer it (or a another pin) back in -- worth it to invest in a roll pin punch (set).
Use a double layer of well-stuck-on duct tape with a tiny hole around where you are punching if you are using a flat punch!