This is covered in B1.5. of the Appendix:
If a point has commenced and a team does not have exactly seven (7) people playing the point, or is in violation of A7.1, then the opposition may call a violation and play shall stop, or the offending team may call a time-out.
If a violation of B1.5 is called after a goal has been scored and prior to the ensuing
pull, the opposition may choose to nullify the goal and restart the point.