Sometimes its necessary to add content at the end of your RSS feed. Here is a little code that will help you to do that. You can add social pages, scripts and more using this method. Just paste the code below into your functions.php file and replace the content with whatever you want it to be. :-) This will not add content to then end of your posts in your website, this will only add content to your RSS feed.

//adding additional content to RSS feed
function addToRSS() {
return '<p>Additional content can be here</p>';
}
add_filter('the_excerpt_rss', 'addToRSS');
add_filter('the_content_rss', 'addToRSS');