Inserindo imagem destacada no feed do site - Wordpress

thumb_on_feed_wordpress.txt

/* Adicionando post_thumbnail no feed */
add_action( 'rss2_item', 'custom_thumbnail_tag' );
function custom_thumbnail_tag() {
    global $post;
 
    if ( has_post_thumbnail( $post->ID ) ) {
        $thumbnail = get_the_post_thumbnail_url( $post->ID );
        echo("<image>{$thumbnail}</image>");
    }
}