get_post_type_archive_feed_link

function get_post_type_archive_feed_link( $post_type, $feed = '' ) {
	$default_feed = get_default_feed();
	if ( empty( $feed ) ) {
		$feed = $default_feed;
	}

	$link = get_post_type_archive_link( $post_type );
	if ( ! $link ) {
		return false;
	}

	$post_type_obj = get_post_type_object( $post_type );
	if ( get_option( 'permalink_structure' ) && is_array( $post_type_obj->rewrite ) && $post_type_obj->rewrite['feeds'] ) {
		$link  = trailingslashit( $link );
		$link .= 'feed/';
		if ( $feed != $default_feed ) {
			$link .= "$feed/";
		}
	} else {
		$link = add_query_arg( 'feed', $feed, $link );
	}

	/**
	 * Filters the post type archive feed link.
	 *
	 * @since 3.1.0
	 *
	 * @param string $link The post type archive feed link.
	 * @param string $feed Feed type. Possible values include 'rss2', 'atom'.
	 */
	return apply_filters( 'post_type_archive_feed_link', $link, $feed );
}