You can take the following steps to set this up using the Content Listing by Folder tool.  
  1. Calendar Event Content Items are stored in the Content Library. We first need to identify which folder the Calendar Event Content Items are being stored.
  2. Once that identified Go to the Folder View and click New > Tool > Content Listing by Folder
  3. Place the Content Listing by Folder tool in the appropriate location
  4. On the Content Index by Folder tab select the Content Folder where the Calendar Event Content Items are stored from the dropdown (note this will display all Content in that Folder)
  5. Click Create to create the page
  6. On the Display Tab you will find the RSS Feed URL and additional options you can select regarding the display