There are three steps to this. Below is how I found the RSS feed for one of my customer’s facebook pages:

1. Find the facebook graph page for the site. For the example this is More generally it would be[your-page-name]

2. Look for your id. On my clients’ graph page it is

"id": "176019295905837"

3. The RSS feed is then More generally it will be[your-id]&format=rss20

facebook graph