I’ve watched a couple of tutorials on this now. HumanIK itself is really useful and takes the normally time intensive task of rigging down a few notches, however I’m unable to add eyes to the rig without them moving out of place.
Using an eye joint with control curves or simply constraining the curve directly to the eye and parenting the eye to the skin, both have parents with not staying even with the head.
There must be a trick to it.