I have. Given timing, I was only able to use it on my finish kit order. I'll have to check back and see if they honor it for a FWF kit but my recollection was that it was limited to the 4 main kits (emp, wing, fuse, finish) of any aircraft.
 
Can you please explain how it works?
My understanding is DD-214 or State DL or VA card
and pilots license.

Did you snail mail, fax or scan and email?