When does a RHP commit?

[Buckeye12]

I was talking to some other umpires last evening and this question arose following FED rules.

Can a RHP, in the stretch, pick his non-pivot foot straight up (like he would in starting his pitching motion), then open up to his left by pivoting on his right foot while still in contact with the pitching rubber (his step turns himself so he is not in violation of the "45 degree line"). His motions are similar to a LHP's "slow" move to first base, but the RHP needs to pivot around to his left.

I know that when I played FED baseball, we were taught that this was a balk; and to steal a base, runners needed to watch this front foot (on a RHP) because once it moved, a RHP was committed to the plate. Now, that I'm an umpire, I've discovered that coaches don't know as much as I once thought, but I am wondering if I was mislead? Rulebook references would be very helpful here. Also, I'd be interested in finding out if this was a balk in OBR and NCAA.