In my experience ... if the runner is going / feinting going to second ... then no balk. If the runner is not going - balk.
ART. 4 . . . Balk. If there is a runner or runners, any of the following acts by a pitcher while he is touching the pitcher’s plate is a balk:
b. failing to step with the non-pivot foot directly toward a base (occupied or unoccupied) when throwing or feinting there in an attempt to put out, or drive back a runner; or throwing or feinting to any unoccupied base when it is not an attempt to put out or drive back a runner;