Embedded thumbnail in RSS feed

I’m a photographer that’s recently switched my photoblog over to WordPress – so I apologize if this has already been asked. I’ve been searching but haven’t found anything and I think I have a unique situation.

I host my photos on a service called PhotoShelter and recently they came out with a new feature that allows people to share photos and images just like youtube videos – meaning it’s a simple flash file doing nothing more than acting like an image and it’s automatically embedded with a watermark and will always point back to your website for protection as viral marketing does its thing. There’s code to embed and share just like a youtube video which makes it a really interesting feature.

I incorporated this into my photoblog and while I love the potential of it, I’m left with an RSS feed that all of a sudden doesn’t have any thumbnails for the images I’m posting. So I’m wondering if there’s a way for me to upload a separate thumbnail image that will only be displayed in the RSS feed?

I’m a former web designer so I’m still relatively comfortable modifying php and web pages. Any help would be greatly appreciated! To see specifically what I’m talking about, you can check out my photoblog at http://www.cavaroc.com/photoblog/