Balk or not fake to 3rd but only fakes throw to 1

[Guest Nate]

Runners on 3rd and 1st  pitcher right handed pitcher makes pick off move to 3rd and takes pivot foot off the rubber then spins and then fakes the throw to 1. In high school it's a legal pick off move but I can't find the rule saying the pitcher has to throw to 1 or can just hold it 

[Senor Azul]

2019 NFHS Case Book Play 6.2.4 Situation C:  With R3 and R1, F1 comes set. He then feints toward third, or he removes one hand from the ball and makes an arm motion toward third base but does not step toward third. He follows with a throw to first base. RULING:  This is a balk. F1 must step toward third base when feinting there. F1 may not feint to first base. He must step toward the base and throw. He might, while he is on the plate, step toward occupied third and feint a throw, and then turn to step toward first and throw there with or without disengaging the pitcher’s plate. If F1 steps and feints to first, he must first disengage the pitcher’s plate or he is guilty of a balk.

[maven]

8 hours ago, Guest Nate said:

In high school it's a legal pick off move but I can't find the rule saying the pitcher has to throw to 1 or can just hold it 

You're looking for the last sentence of 6-1-3: "After the pitcher has placed his pivot foot on the ground clearly behind the plate, he then has the right to throw or feint to a base the same as that of any other infielder."

That's going to apply to your play because the pivot foot coming off the rubber during a legal feint to 3B is a kind of legal disengagement. The pitching restrictions are no longer in force, so F1 now enjoys the right to throw or feint "the same as that of any other infielder."