Control the display of each group's specific post via RSS from RSS SETTINGS on the Group Settings page. To get there, click on Settings from the group page.
Navigate and expand RSS SETTINGS.
You can also control what topics are displayed on the RSS feed by checking or unchecking the Enable RSS Feed box for each individual topic.
Note: When a message is posted it will automatically be sent to that groups specific RSS feed URL. It can be turned off as described above.