A solid ink feed system for a phase change printer includes a solid ink feed channel that has formed in it a feed channel key that either blocks a solid ink stick from complete insertion into the feed channel, or blocks passage of an ink stick along the length of the feed channel, unless the ink stick has a key element corresponding to the feed channel key. A solid ink stick is formed of a three dimensional ink stick body with a key element that extends along a surface of the ink stick body through the rear of the ink stick body.