We often find the need to sign documents like SIAs.

Open the document and click Tools.

Click Certificates.

Click Certify (Visible Signature).

Click and Drag a small area on the document where you'd like the signature to be placed.

Click Continue.

Toggle the Permissions to “Annotations, form fill-in, and digital signatures”.

Click Review then click Sign.

Save the document and it will look like this.