PC signal sequence

[NNJOfficial]

Stopping the clock with a raised fist and then signaling the direction of the ball while placing a hand behind your head is the proper NFHS mechanic and if you are new and/or being evaluated a a HS official, that's what you should do.
That being said, most veteran officials adopt a variation of the NBA style fist punch. If I do that, I give the proper PC foul signal when I report to the table.

Using a multiple whistle for a player control foul is a way to make it clear, particularly to your partners, that you are calling a PC foul. Block = single whistle and charge = multiple whistle. This is not a rule, this is simply a matter of personal preference and are one of the little nuances that help show your command of the game.

The proper mechanic for a team control foul is to give the normal raised fist foul signal and then to drop the fist so that it is facing forward. The proper mechanic is not a punch. Again, most officials have either adopted the punch or give the raised fist foul signal and point in the direction of the ball. Again, a multiple whistle helps signal what you are calling, but is by no means a requisite.