In D&D 4E Player's Handbook 3 pages 139-155 are the recipes for merging two hybrid classes together. Hybrid psions on pg 147 does not mention Ritual Casting. Does the hybrid class lose this ability?
Hybrids tend to lose a fair number of features of their parent classes. As hybrid psion does not list Ritual Caster as a class feature, you don't get it from that part of your hybrid.
In general Hybridization penalizes you for having full access to two classes by only giving you half of the abilities of each class. This penalty is worth it for the full access you get especially if you spend feats and such to regain class features as you level up. If however your merely looking to gain some of the benefits of another class and access to a few of their feats than multiclassing might be a better and easier route to go down.