When you enter a search in DiscoverE, you should see the RSS symbol at the bottom of the left side panel in the search results display.
These RSS feeds still don't work directly in all feed readers. The url format is non-standard.
However, they do usually work if those feeds are converted by Feedburner. It only takes a few seconds to paste the DiscoverE feed url into the Feedburner interface at http://feedburner.google.com and copy the reformatted feed into your reader or LibGuide.