// put this into functions.php
add_filter('the_excerpt_rss','rss_filter') ;
add_filter('the_content_feed','rss_filter_full') ;
function rss_filter($content){
global $post;
$thumbId = get_post_thumbnail_id();
if($thumbId) {
$img = wp_get_attachment_image_src($thumbId, 'large');
return '<img src="'.$img[0].'" alt="'.$post->post_excerpt.' title="'.$post->post_excerpt.'""/>'.$content;
}
}
function rss_filter_full($content){
global $post;
$thumbId = get_post_thumbnail_id();
if($thumbId) {
$img = wp_get_attachment_image_src($thumbId, 'large');
return '<img src="'.$img[0].'" alt="'.$post->post_excerpt.'" title="'.$post->post_excerpt.'"/>'.$content;
}
}