To add a signature in Roundcube webmail:
1. Log into Roundcube
2. Click Settings at the upper right
3. Click the Identities tab
4. Select an identity
5. Click the Signature tab
6. If you want to use formatting, click the Html signature box
7. Enter the signature in the Signature box
8. When done click Save
Send yourself a test message to see that the signature looks the way you want.
