Email Signature in Roundcube Webmail

Log in to Webmail from Client Area, using a direct link, or from cPanel.
Click the Open button under the Roundcube logo.
You can check the checkbox (next to the Open button) Open my inbox when I log in.
From then on, you will see the inbox of your default email account when logging into webmail.

Click the Settings button in the left vertical menu.

Click the Identities the third link under the Setting title.

Find and click on the desired identity.
Signature
If you wish to use HTML in your signature, click the HTML Signature checkbox.
This option will cause the Signature field to change over for HTML allowing for special formatting.
Enter your desired custom signature in the Signature field.
Once entered, click on the Save button located underneath the tabs.You have now created your new email signature!

Click on the Image Icon (Third Icon from the Right)
Source
Click on the Folder icon and upload an image from your device.
Dimensions
Set the Width and the height of the image.
Put ON the Constrain proportions.

Add a link to your selected text (Business webpage or more) by clicking the fifth icon from the right.

Insert Link window
Fill out the options and click OK.
Don’t forget to write the full link URL with the needed protocol https://

Once entered, click on the Save button located underneath the tabs.