JFBConnect should take care of adding that tag for you if you've created a Facebook application to use with JFBConnect. You can learn about how to create an application and get an app_id on the following page:
www.sourcecoast.com/jfbconnect/docs/configuration-guide?start=1
If you're just using the Like button from within JFBConnect, you don't really need to create an application. If that's the case, let us know, and we'll help you add the proper admins tag (since JFBConnect won't have an app_id tag to add).
Thanks,
Alex