Download A+ Signature from the App Store
I used "Load from Photo Album"
Select your picture. (That's my ducks egg, it's huge!)
Options are at the bottom of the screen
I used the Pencil tool to hand write my own watermark. The "T" text tool lets you use different fonts and styles
Write your watermark on the grid shown
Press "back" when finished.
You may double tap the signature to modify; move around, enlarge, shrink, etc.
Position your watermark wherever you want on your picture
Options to save, email, and send are on the menu
Check your photo album!! There's a surprise waiting for you...