I heard F space pickups are designed to be parallel with FR trems, is that correct?

i put an invader in the brindge of my LTD and i can see that the space between the 12 caps are smaller than the space of my saddles.

How will this affect my tone?
probably not enough to get overly worried about it. F-Spaced and Trembuckers are typically used in Strats due to sting spacing so you are partially correct. Typically you want the stings to line up with the magnet poles on bucker for the best string vibration pick up. Not sure on the LTD so maybe someone else has a differing opinion.