Custom post template

Great theme so far …

I want to use a custom post template including some custom fields and static information.

Copied single.php to my child theme directory and renamed it to new_postname.php just fot testing purposes.

Inserted
<?php
/*
Single Post Template:new_postname
*/
?>
at the top of te file.

I took care to leave
<?php
/**
* @package Make
*/
in place.

Any ideas how to display and use this custom post template.

Cheers,
KeesD