Word 2013 provides users with the option to add signature line to the document, The signature line is a block that will be inserted in your document as shown below.
You can add your signature to this block by using any Digital Signature services or just take print out the document and add your signature.
Adding Signature Line
Step 1: Click the Insert menu in Office Ribbon and navigate to Text section.
Step 2: Click Signature Line under Text section and select Microsoft Office Signature Line from the list.
Step 3: In the Signature Setup, enter the information for Suggested signer, Suggested signer’s title and their email address then click OK button,
This should add the Signature line to the document in Word 2013.