Team 'A' is shooting the first of a two shot free throw. 'A' coach calls 'A' player to his bench to give instructions. Player leaves the playing floor to talk to coach.

walk over and tell them player needs to be on the floor

If the player who goes to the bench to talk to the coach is the player who's supposed to be shooting, you briefly "encourage" compliance with the rules (shooter must be inside the circle when the ref is ready to administer the ft), and then set the ball on the line, whistle the violation, and give the ball to B.

If it's not the shooter who's with the coach, just be sure they're behind the free throw line extended, and then go on with the shots.

That is not correct, Juulie. Check 10.1.5 Sit B. There was no time-out or intermission, so you don't use the RPP.

I think that you may have misread that one, Juulie. The player <b>left</b> the court. The player deliberately went OOB.

Yes, that is the point. I know that it is a violation, but I'm not sure how to enforce it in this situation.

The player going OOB is not the shooter. The shooter is at the line preparing to shoot.

After the first free throw, tell the coach and the player that he/she must remain on the playing floor.

If you're gonna call it, treat it the same as any other violation made during a FT by the shooting team. Call the violation as soon as the FT shooter's teammate leaves the court, cancel the first FT, and then administer the second FT.

Asd others have said, there are other game-management options that might be a wiser choice.

What I described is not the RPP. However, you're right about the technical. I couldn't find a good reference for it.