Add featured image url and formatted published date in RSS feed on WordPress

customRss.php

function add_new_rss_fields() {
    global $post;

    if(has_post_thumbnail($post->ID)) {
        $thumbnail = get_attachment_link(get_post_thumbnail_id($post->ID));
        echo"\t<image>{$thumbnail}</image>\n";
    }

    $published_date = get_the_date( 'm/d/Y', $post->ID );
    echo"\t<publishedDate>{$published_date}</publishedDate>\n";
}

add_action('rss2_item', 'add_new_rss_fields');
add_action('rss_item', 'add_new_rss_fields');