http://www.ballyhooblog.com/add-custom-post-types-wordpress-main-feed/
http://www.wpbeginner.com/wp-tutorials/how-to-add-custom-post-types-to-your-main-wordpress-rss-feed/
http://somadesign.ca/wp-content/uploads/downloads/2010/05/sd_register_post_type.1.3.php_.txt