Multisite / more than one rss source?

I have a multisite wordpress website with just two webs (recipes.mysite.com and mystie.com) so, i have just one fanpage.

I make the configuration of the plugin but i don’t know if i need to add an rss feed… so i add the mysite.com/feed/instant-articles/ and this works but now i’m a little confused with how the rss feed grabs the content from wordpress i don’t know if the articles are randomly load or something… i just have 10 articles and this articles are from two years ago.

Another problem is with my second website on the network… i make the configuration on this site to but now i don’t know if i need add another rss like… recipes.mysite.com/feed/instant-articles

Regards.