Stolen from the Steel Guitar Forum:
"I use the ring finger to block all 2nd finger notes as far as I can tell. When I get in the thick of things at tempos above average, I don't know exactly what's going on because some of my blocking is done by pulling the bar off a note and letting the 2nd finger block as I move from the top to bottom strings.
Depending on the pattern, in addition to the ring finger, I will use the thumb of the bar hand, second finger of the bar hand, and the palm of the right hand. Most palm blocks follow a thumb pick or 1st finger note."