WordPress: Post Thumbnails im RSS Feed anzeigen

//RSS Post Thumbnails
  function featuredtoRSS($content) {
        global $post;
        if ( has_post_thumbnail( $post->ID ) ){
            $content = '<p>' . get_the_post_thumbnail( $post-&gt;ID, 'large',
              array( 'style' =&gt; 'padding: 4px; margin:0 15px 15px 0;' ) ) . '</p>' . $content;
        }
        return $content;
    }
    add_filter('the_excerpt_rss', 'featuredtoRSS');
    add_filter('the_content_feed', 'featuredtoRSS');

Quelle und Grundlage: http://pastebin.com/FNvVh4BT