How to enable Checklist Approval Signature?

Pre-requisite: 

Mobile app version 4.0.20

Step 1:

On the Checklist Manger, select the Require an Approval Signature as shown below.

 Step 2:

On the mobile app, after completing the checklist, note that there is now a Capture Approver Signature button.

Tap on the Capture Approver Signature button.

 If you do not put the signature, the inspection cannot be closed.

 Capture Approver Name and Signature.

On the Inspection report, the signature will appear as shown below.