Ok I got it

// Add the audio link to the feeds so we can podcast
function feed_customMeta($content) {
global $post, $id, $radioMeta;

  if ( !is_feed() )
    return $content;

 $getRadioLink = \'<a href="\'.$radioMeta->get_the_value(\'radioLink\').\'">Download Audio</a>\';

  if( $getRadioLink)
    $content .= $getRadioLink;
    return $content;
}
add_filter(\'the_excerpt_rss\', \'feed_customMeta\');
add_filter(\'the_content_feed\', \'feed_customMeta\');