update-to-feedburner.php

<?php
/**
 * Plugin Name: Update WP feed to feedburner
 * Plugin URI: http://www.wpquestions.com/question/showLoggedIn/id/8997
 * Description:  Update WP feed URL to feedburner URL
 * Version: 0.1
 * Author: Fahd Murtaza
 * Author URI: http://www.fahdmurtaza.com
 * License: GPL2
 */

// replace the default posts feed with feedburner
function appthemes_custom_rss_feed( $output, $feed ) {
    if ( strpos( $output, 'comments' ) )
        return $output;

    return esc_url( 'http://feeds.feedburner.com/ChangeToYourThemeURL/' );
}
add_action( 'feed_link', 'appthemes_custom_rss_feed', 10, 2 );

?>