In a flat spin, does the F-16 use its rudder deflection against the rotation for recovering? If the H-tail is used in recovery from the flat spin, is the rudder used for stopping the yaw or beta of the F-16? 

I know that it is surely used for inverted flat spin, but I believe that the rudder is blanked by the H-tails in upright spin and is not effective.
It is not possible to have the rudder deflection because the huge amount of AOA and control law take that in consideration and cancel (fadeaway) the pilot rudder inputs.Activating the MPO the slabs moved  max in order to get the nose down to lower AOA and after that we can get responses from the rudder .https://www.flightglobal.com/f-16-spin-recovery-technique-invented/15027.article