Adobe ACROBAT READER 7.0 Manual page 155

Selecting digital IDs
Before you sign a PDF document, you may be prompted to select a digital ID file. To
avoid being prompted repeatedly, you can select a digital ID to use all the time or until
you quit Adobe Reader.
To select self-signed digital ID file settings:
1. Choose Document > Security Settings.
2. Select a digital ID on the left.
3. From the Set Default menu, specify that you want to use the digital ID for signing.
If you choose not to be prompted for the digital ID, the pen icon
selected digital ID.
appears next to the