Adobe ACROBAT READER 7.0 Manual page 141

Signing PDF documents in Adobe Reader
You can use Adobe Reader to sign a PDF document only if the document includes
additional usage rights and an Acrobat digital signature field. When you sign a document,
your signature and the related information can be stored in a signature field embedded on
the page. A signature field is an Acrobat form field.
Important: Sign a document only after you make final changes. If you make changes to a
PDF document after you sign it, the signature may still be valid, but the caution
triangle appears in the signature field and in the Signature tab, indicating that changes
were made after the signature was added. The author of the PDF form can also lock fields
after the document is signed to prevent additional changes.
To sign a document:
1. Click the unsigned signature field in the PDF document. (The field must be a signature
form field, not just a blank box.)
2. If the document isn't certified, make sure that you received it from a trusted source, and
then click Continue Signing.
3. If you have not yet selected a digital ID, select one, and then click OK. (See
IDs and certification
4. In the Apply Signature To Document dialog box, type your password if prompted, and
specify the reason for signing the document.
5. Click Show Options, and do the following:
If desired, add contact information for validation purposes.
Choose a signature appearance. Standard Text displays a validation icon with the name
and other information. If you defined a personalized signature, choose it from the menu.
To preview your signature before signing the document, click Preview. To create a new
signature appearance, click New, and follow the steps in
6. To sign and save the document, do one of the following:
Choose Sign And Save As (recommended) to sign the document and save it using a
different file name. This command lets you make changes to the original PDF document
without invalidating the signature.
Chose Sign And Save if you already saved the document with a different file name. If you
make changes to the saved PDF document, you may invalidate the signature.
methods.)
Changing signature
About digital
appearance.