Oh dear, a rockery in shade - never a good idea. Most rockery plants are alpine types that like full sun. I'm afraid you're stuck with growing things like Lamium maculatum, Ajuga reptans (although this one likes a bit of moisture, and a rockery is a dry place to be) Campanula muralis and I can't think of anything else at the moment. Sorry to be so discouraging. Any chance you could remove the rockery and grow shade loving plants instead?

You could also try some herbs like thyme but alpines need sunlight to flower.

There are quite a few smallish plants that would be suitable for a shady rockery and if they grow in your rockery, then they are your rock plants.

Primula Heuchera, Epimedium Viola Erodium Astilbe Ophiopogon heucherella Ajuga Pulmonaria Liriope Tierella and not forgetting the hardy geranium, Anemone blanda.