Lead Owner Signature Merge Field

Lead Owner Signature Merge Field

I want to automatically insert a signature (i.e. contact info usually found at the bottom of an email) into an email template, depending on who the lead owner is. What is the merge code for the Signature from a Users profile?
CRM > Settings > Customization > Templates

There is a popup near the bottom of the edit screen which says: "You can insert a Signature, which is available as a merge field in the users section." It is also referenced on this page: https://help.zoho.com/portal/en/kb/crm/customize-crm-account/customizing-templates/articles/template-builder#Merge_Fields

I can't find the merge code for a lead owner signature. Nothing labeled "signature" shows up in the popup list of available fields.