How many French fought at Normandy in 1944 on D-Day?

Answer

The true number of resistance fighters who answered the call on D-Day will probably never be known because each cell was self contained for security reasons(if you don't know you can't tell the neighborhood Gestapo). Free French soldiers and agents also parachuted into France to assist the Resistance. I do not believe that DeGauls Free French forces fought in any large numbers on D-Day but contributed immensely during the breakout and drive to Paris.  

Answer

Most D-Day fighters came from UK, the US, and Canada. But there were also Frenchs, Poles, dutechs, Norwergians, etc, etc...
For France besides the Resistance, there was an offical Free French Marine Commandos Batailion on D-Day, lead by Cdt. Kieffer, an Alsatian, which took among others the Casino of Carentan, and was allowed by the Britisch troop to have the honour disembarke first on the French beaches. They lost most of their men. Several hundred other Frenchmen where fighting on that same day under US and UK uniforms. Lt. Clostermann, another Alsatian, was the RAF pilot that shot the most German planes during WW2.