Best way to syndicate cartoon + form

I run an online cartoon caption contest (eg - I draw a cartoon and people submit captions) and am looking to syndicate it on other websites. Eg - people put the cartoon and a form on their webpage so you can submit captions directly from their site to mine. I used to do it simply by supplying HTML to copy and paste but then when I changed my site structure, all the links became defunct. I'm looking to update it, make it more robust and was wondering the best way to do it.

It seems RSS is the preferred way to syndicate content but I'm not sure if it can do a cartoon/form with 2 fields. Is Javascript a good alternative? Or can someone recommend another more appropriate way?