Adding to RSS Feed

I wanted to create a simple framework so that I could ad bits of code below my post excerpt in my rss feed. Based on a little searching, I decided that pasting the following into my functions.php file was the best idea.

function rssadds($content) {
    $content = $content.include(TEMPLATEPATH . '/rssadds.php' );
    return $content;
}
add_filter('the_excerpt_rss', 'rssadds');
add_filter('the_content_rss', 'rssadds');

That code works fine, but for whatever reason, the rssadds.php include is appearing before the content, not after. The include occurs after the $content in the code, right? Not entirely sure what’s going on here. Could anybody tell me why this would be seemingly backwards?