functions.php
/**
* feedをサムネイル付き抜粋文にする
*/
add_filter('the_excerpt_rss', 'diw_post_thumbnail_feeds');
add_filter('the_content_feed', 'diw_post_thumbnail_feeds');
function diw_post_thumbnail_feeds($content){
global $post;
if(has_post_thumbnail($post->ID)){
$content = '<div>'
. get_the_post_thumbnail($post->ID, 'thumbnail')
. '</div>' . $content;
}
return $content;
}