Well Google Play is an available integration now so if it is not on your integrations tab then suggest logging a ticket with support to turn that capability on.
Apple App Store is a bit more difficult as Khoros were not able to get a link created for that due to Apple's inability to work with others. I am still hopeful that a special RSS feed will be created for that store to better capture the meta data (scores and whatnot) but for the moment the way to integrate is a little bit **bleep**. By that I mean that the Apple RSS feed is country specific so if your app is available in more than one store location you need to integrate them all. I am lucky due to my company being wholly based in Australia we only needed to do one, others have needed to link many feeds for each app.
The format (I have left out the https:// so the text doesn't hyperlink) itunes.apple.com/<country-code>/rss/customerreviews/id=<app-id>/sortby=mostrecent/xml, where the country code is a 2-character short code for the country (e.g. "au" for Australia, "us" for USA, etc.)
