A rich text signature is a bit of text (such as your contact information or a favorite quote) that’s automatically inserted at the bottom of every message you send. Here's a sample signature:
Go to setting tab in your G mail account
Click on icon to expand.You will see below image
How do I switch on Rich formatting for my Gmail signature and emails?
1.Click on the Compose button in the left hand menu on Gmail.
2.Click on the Rich formatting link above the text message box.After successfully changing this you will see below image
Then go to setting --> signature
To add a signature upload the image to any picture uploading site.Here is our signature
PS: Don't forget to save changes at bottom!!