How to create /associate update rule in Signature field

Hi All,

I am using Signature functionality in my application. .My requirement is to attach the Service Order number or Time Stamp along with the signature field.

In the screen I can see both these option to select the check box but I have a query:

1. Time and Date: If I select this check box , will it append the current date time stamp with the signature?

2. If I select the check box for update rule , where do i create /attach the update rule? All I see is a box to pick the global .

Please advice how to achieve them.

Thanks and Regards

Neha Mahanty