[SEDXC] QSL Question

[JT Croteau]

Hi guys, QSL card question here..

Back when I was operating as W6FO down in GA, I would sign all my
contest QSO's with W6FO/4.  I need to reply to some contest DX QSL's
I've been receiving over the past couple weeks.  However, all I have
left for cards are some printed W6FO cards.  Can I add a "/4" by hand
to these cards or does it make them invalid if I hand write this in?

Thanks

-- 
JT Croteau, N1ESE - Manchester, NH (FN42gx)
Contest Manager, TARA Skirmish