Sorry - I don't have an X-T2, so I can't comment on the picture. My X-Pro2 doesn't have this, and sadly, the X-T2 user manual doesn't offer any help. However, I assume that the "F" option indeed is for aperture selection. Yet, this only applies to lenses w/o aperture ring. If this is so, then this choice doesn't offer any function for you. What's the problem of having a choice that isn't functional in your case, if it doesn't mean any other functional restriction for you? What do you lose if you simply ignore this option? What happens if you swap the function assignment between the front and rear control dial (Please login or register to view links)?