It is simple. If I don't have the stamp handy I'll just handwrite "Redeemed Lawful Money per 12 U.S.C. 411" backside of the check. I use the Smartphone for deposits too - very handy.

It's not too hard to see whats going on here, even in the eyes of the unpottytrained observer. Seems doug555 has even given us a clue with his username.