Auto-incrementing stamp for Acrobat.
Place Increment.pdf in the acrobat stamps folder: C:\Users\*User Name*\AppData\Roaming\Adobe\Acrobat\11.0\Stamps\
Increment.pdf
C:\Users\*User Name*\AppData\Roaming\Adobe\Acrobat\11.0\Stamps\
1 2 3
a b c
A B C