Keep Password-Protected Posts Out of Feeds
Removes password-protected posts from all feeds, where they otherwise appear with a "There is no excerpt because this is a protected post" message.
Snippet Library
RSS Feeds snippets for WordPress
Snippets for WordPress RSS feeds: add featured images and custom post types, delay publishing to feeds, credit your site on scraped content or turn feeds off. For publishers and podcasters whose readers follow along by feed or email.
Summaries Only in RSS Feeds With a Continue Reading Link
Sends only a short summary of each post to feed readers, whatever the Reading setting says, and ends it with a link back to the full post on your site.