Email signatures basically have the same restrictions as HTML emails, so it's a good practice to use Responsive.email Studio for this as well. Just create your signature like a usual HTML email and consider the following points.
The first difference is probably that you want your signature to be left aligned - just change this property on Your Email element. A responsive version of your signature is also supported with the usual elements and restrictions. Depending on your client for sending your messages, the email may keep a padding around all content - so you may consider to reduce the width of your responsive version from 320px to 300px so it will again fit to a mobile receiver.
It depends on your email client (Outlook, Thunderbird, ...) how images will be included in your emails. It's a good practice that they are bundled with your email - in this way each message gets bigger, but the receipient won't get a blocked images message. However the actual integration of your signature can be quite tricky, especially with Outlook.
How does Responsive.email work for your signatures?