I'm having a terrible time with the F cord right now too. I'm doing Lisa's fingerpicking tutorials, and I'm following her advice of just playing the top 4 strings instead of trying to barre it. But my problem is that I can't play strings 1 and 2 cleanly with just my index finger. One of them always ends up not pressed all the way down. And my other two fingers keep muting adjacent strings. It's rather frustrating. I'm hoping it'll just magically get better someday if I keep practicing. My guitar has a slim neck (1.72" nut) so I also wonder if I would do better with a wider string spacing.