Quickly add a footer to your WordPress feed

rss-footer.php

<?php
/*
Plugin Name: RSS Footer Example
Plugin URI: http://pmg.co/
Description: adds a little something extra after your rss content.
Version: n/a
Author: Christopher Davis at PMG
Author URI: http://pmg.co/people/chris
*/

add_filter( 'the_content_feed', 'cdgn_rss_footer' );
add_filter( 'the_excerpt_rss', 'cdgn_rss_footer' );
function cdgn_rss_footer( $content )
{
	$warning = "<p>This feed is mine!</p>";
	return $content . $warning;
}