Some pdf documents arrive in our inbox with the signature field already created for us. In those cases you simply click the field where your signature is required, choose the electronic signature you've already created, enter your password and the document is electronically signed by you. Your digital signature has your name, the date and time you signed the document it is also encrypted, meaning it is tamper proof. This proof that it is you who signed it. The signature field will usually appear as a gray box next to the signature line near the end of the document.
There are other times when a pdf document arrives in our inbox with a signature line, but no signature field. This is because the author failed to create that signature field for our use. It could be that the author expects a standard 'pen and ink' signature; however, a digital signature is becoming the standard way to sign pdf documents. When this occurs, we need to create the signature field for the author.
First, select More Tools from the menu to the right of the document. If the Tools menu isn't available, select Edit from the top menu and then choose Manage Tools.
Next, choose Customize from the options on the left part of the screen.
The Create Custom Tool dialogue appears. Choose Prepare Form.
Next, select the Add button, hit Save and name your custom tool Prepare Form. You should now see Prepare Form listed as one of your tools. Click on the Prepare Form tool.
One of the options available to us is Identify Form Fields. Acrobat will scan the document and identify what it thinks are fillable fields. If the author has included a signature line it will be found and created as a fillable field. We select the field, choose our digital signature, insert and save the document.
Congratulations: you've now digitally signed the document.