You don't need a pen to sign an electronic document. Security features in Adobe Acrobat 7.0 let you sign documents, whether to simply show approval or to control access and modifications to the documents you distribute.
To digitally sign a document, you design the appearance of your signature, decide where you're going to sign, and obtain or create a digital ID, which allows others to validate your signature.
To limit access to a document, you must have digital IDs for the people you want to give access to.
Design your signature.
Choose Edit > Preferences (Windows) or Acrobat > Preferences (Mac OS), and then choose Security. Click New in the Digital Signatures section of the panel to create a new signature appearance. Choose the items that you want to appear with your signature, including the date when you signed, the reason that you signed, the Acrobat logo, and other information. The preview changes as you make your selections. If you want to include a graphic, select Imported Graphic, and then click File and select the PDF file that you want to include. Give the signature appearance a title, and then click OK.
You can create multiple signature appearances, each for a different purpose. For example, you may want to use one signature appearance for signing contracts and a different signature appearance for signing correspondence.
Choose to sign the document.
In Acrobat, open the PDF file that you want to sign. Choose Document > Digital Signatures > Sign This Document. If the document has not been certified, Acrobat displays an alert dialog box. Click Continue Signing to sign the document.
You may also choose to certify the document. When you certify a document, you attest to its contents and specify what changes may be made to the document. If other changes are made after you sign, the document becomes uncertified.
Select the signature field.
If a signature field already exists on the document, choose Sign an Existing Signature Field. When you click OK, Acrobat scrolls to the signature field; click the signature field with the Hand tool to select it.
If no signature field exists, choose Create A New Signature Field To Sign. Acrobat displays an information screen; when you click OK, you can draw the signature field on the page.
Alternatively, you can create an invisible signature. Invisible signatures do not appear on the page in the document pane; they are visible only on the Signatures tab.
OK, so you want to stamp your document. Maybe you need to give reviewers some advice about the document's status or sensitivity. This tip from author Ted Padova demonstrates how to add stamps with the Stamp Tool along with related comments.