A question about changing keybinds

Might be a pretty dumb question, but I just can't seem to figure it out.

I want to change my hotbar 3 to where you have to press a combination of F + [a number]. Kinda like how hotbar 2 is by default set up with Ctrl. The keybinding menu in the game won't let me do F+1, F+2, F+3, etc., so I have no idea how to do this.

I found all kinds of pictures of other peoples' UI setups on the internet where they will have hotbar 2 on the A key, hotbar 3 on the Q key... but no where could I find how to exactly to set that up.

I don't think the game is set up to allow you to us the F key as a modifier.

When you are in the hotkey editor you highlight the hotkey that you want to modify and then press the key or key combination you want it to be. As far as I know ctrl, alt and shift are the only things you can use as modifiers. If you try to do F and another key it tries to use whichever key you release first.

If you have seen images where people have an entire hotbar set up with A or Q as modifiers they might be either using a third party program or editing game files directly.

I feel dumb now, but you are right. I was using this picture as a reference and didn't realize that the A on his third hotbar stood for alt. I feel pretty dumb now. Thanks for the help. It would still be nice if we could use other keys as modifiers though.
http://i.imgur.com/yT615nt.jpg