Since this is available nowhere else on the internet, I’m posting it here for safekeeping. I believe that this applies to at least FirstClass 10, perhaps also FirstClass 9 (but that’s just a W.A.G.). This is from FirstClass tech support:
An RSS feed can be generated for any FirstClass container object (folder, conference, etc.) which is visible to the Web by adding a template override parameter to the URL. In other words, if the URL to the news conference on your Web site was http://www.mysite.com/News , then the URL to the RSS feed for that conference would be http://www.mysite.com/News?Templates=RSS&items . If you have an RSS feed reader you can simply enter that URL, give it a name, and you’ll have a feed. Usually, sites that offer an RSS feed will put a little icon on their main Web page to show that they have one. If your main page is a FirstClass document all you need to do is:
Paste in your preferred RSS image
Highlight the image in the editor and right-click your mouse, choose “Make Link”
Enter the RSS feed URL, in our example http://www.mysite.com/News?Templates=RSS&items or ?plugin=RSS&Items
Buyer beware: I have not seen this work yet in my own tinkering. But I am hopeful that somehow I’m doing something wrong.