NFHS Re-entry
 

Fed rules
Visiting team's starting pitcher is listed as the ninth batter in the order.
During the top of the 7th inning, a pinch hitter takes his spot.
In the bottom of the 7th, if I am correct, the starting pitcher may still re-enter to pitch. Is this correct?

Yes, this is correct (assuming it's the first time F1 has re-entered the game).