It's all in how you distribute the pressure across your index finger. Hard to explain. But for radiused fret boards more pressure is required on the outside strings than in the middle to achieve a clear chord.

Also, for many chord progressions, a partial F-chord is more than sufficient. Keep your pinky, ring, and middle fingers in the same position, but only bar the top two notes on the first fret (E and B strings) and don't hit the low E string when you strum.