You probably need to set this one up manually, or at least start with a basic mapped key in the Wizard (straight key broadcast of F would work), and then adjust it. Assuming retail WOW, then the following should work.

You want 2 actions on your Mapped Key.
Mapped Key, Hotkey F

Actions:
Keystroke Action, F, Target of Window: Current (self)
Named World Of Warcraft Action, /Follow {FTL}, tick the +Slot ID (FTL) modifiers (because we wont set this for the whole mapped key), Target of Window: All w/o Current (all others)