Can a pitcher stand on the corner of the pitching rubber?

Answer 1

Yes. A pitcher must make contact with the rubber but it may be a toe, a heel, or the entire foot.

Answer 2

Yes, the pitcher has to be in contact with the rubber or if not the pitch will be illegal

Answer 3

The pitcher must have both feet on the rubber when receiving her signals and one foot must be in contact with the rubber when the ball leaves the pitcher's hand.