Fix a Double Toning F
The most common problems with a reed other than it being to hard is a double toning F. This occurs when a reed has been sunk to far down into a reed seat.
Option 1: Rubber Band
Place a rubber band on the reed like you would to make it easier. This is sometimes the best and easiest thing to do. I recommend doing this and then playing and squeezing you reed a bit. A double toning F usually only occurs in new reeds that haven't been broken in.