[SAump]

FED 6-1-1 "He shall take his sign from the catcher with his pivot foot in contact with the pitcher's plate."

The intention here is to establish the pitcher, apart from the other infielders.

FED 6-1-1 "The pitching regulations begin when he intentionally contacts the pitcher's plate."

The intention here is to establish the time frame when a pitcher becomes subject to all pitching regulations.

One cannot call a balk until the pitcher has first made contact with the pitcher's plate. Valid justifications for which a proper balk penalty may be charged against the pitcher are found in FED rule 6-2-4. This rule requires the pitcher to be touching the pitcher's plate.

FED 6-2-5 "It is also a balk if a runner or runners are on base and the pitcher, while he is not touching the pitcher's plate makes any movement naturally associated with his pitch, ... "

Merely placing his feet on or "astride" the pitcher's plate does not qualify as movement associated with his pitch. Taking signs does not qualify as movement associated with his pitch. Now I do suppose that one could interpret "or he places his feet on or astride the pitcher's plate" with the ball in his hand as a prerequisite for a balk, but it would be difficult to justify a balk in the OP.