Since Wordpress 3.5.x showing RSS feeds from sub domains on a website within the same domain can give errors.
The tech team has set up a flexible workaround for this.

• Check this page :
  http://planet.squat.net/wp-content/feeds/all-feeds.txt
• See if the *.squat.net RSS feed that you need is there.
• If not, ask tech@ to add it for you.
• If it is there, then use this syntax :

yourwebsite.squat.net/wp-content/feeds/remote-website-name.feed.xml

where "yourwebsite" is your squat.net website, and "remote-website-name" is the name of the squat.net website where you need the RSS feed from.

See this screenshot with an example for adding an RSS feed like that :