//WordPress FEED utm_source
//remove_filter( 'the_permalink_rss', 'filter_the_permalink_rss', 10, 2 ); 
add_filter( 'the_permalink_rss', 'filter_the_permalink_rss', 10, 2 );
function filter_the_permalink_rss() { 
	$link =  esc_url( get_permalink() . '?utm_source=feed' );
    return $link; 
};
//remove_filter( 'comments_link_feed', 'filter_comments_link_feed', 10, 2 ); 
add_filter( 'comments_link_feed', 'filter_comments_link_feed', 10, 2 );
function filter_comments_link_feed() {
	$hash = get_comments_number( $post_id ) ? '#comments' : '#respond';
    $comments_link = get_permalink( $post_id ) . '?utm_source=feed' . $hash;
	$link = esc_url( $comments_link );
    return $link; 
}
add_filter( 'the_guid', 'filter_the_guid', 10, 2 );
function filter_the_guid($link, $int){
	if(!is_feed())return;
	$link = esc_url( $link . '&utm_source=feed' );
    return $link; 
}