Pitch in circle, raises throwing hand with ball, LBR?

[RKBUmp]

Rule supplement 34-J. While in the circle and in possession of the ball, any act by the pitcher that, in the umpires judgement, causes the runner to react is considered a play.

The pitcher doesnt even need to raise her hand, if she turns sharply toward the runner, makes an agressive step toward them etc and the runner reacts, it is a play. Holding the ball up like they are going to throw is most certainly an attempt to make a play and freeze the runners.