Hello!
Thanks for the question! RoundCube allows you to use HTML for the composition of the message. You would need to enable this option in the Preferences.
Login to RoundCube
Click on the SETTINGS option in the top right hand corner
Click on Preferences in the menu that appears at left
Under SECTION, click on Composing Messages
Click on the first option "Compose HTML messages" and make it "always". You can also select a font here (at the bottom of the list), if you wish.
Click on SAVE
Next, click on Identities at left.
Select the email address you want to add the signature to
Scroll down and select HTML and you will see the editor appear. In order for the image to displayed, you would need to use HTML to reference the image. For example, <img src="http://domain_name.com/image.jpg" />. Remember that this image should be a small file. The image file itself can be saved on your server. The code for referencing from it shoulder. You would need replace the domain_name with your domain name, and the image file name with the file name of the graphic you're using.
Hit the SAVE button after you finish. If you want add another, simply click on the PLUS sign at the bottom of the signature list
The steps above can also be found here: Adding a signature in RoundCube. The main difference is that we explain how to add the graphic file above.
If you need help uploading a file to your website, you can refer to the following article called How to upload files to a server. Once the file is uploaded, then you can reference it with a URL as per the example above in step 9. You would replace the "domain_name.com" with the name of the file. Remember that the file should be relatively small.
I hope this helps to explain it! Once you have the signature is set -it will be used every time you write an email. Note that you can have more than one signature. If you do, then you'll need to select the one you want to use.
I hope this helps to answer your question! Please notify us if you are unable to rectify the issue.
Regards,
Arnel C.