Nick's explaination is for the Aussie halyard rings. The stock Hobie setup (at least up to my '80 model - may have changed since then) is the separate ring and shackle, which does not have the small inner ring.
With the Hobie ring, yes, you just tie the halyard directly to the ring with a low-profile knot. The rigging manual recommends a simple over-hand knot, with a second overhand knot in the trailing end, to keep it from pulling through (they use this knot to attach the trap dogbones too). After tying this knot, you will notice that one side of the ring is noticeably "lower profile" than the other - make sure this "lower" side faces towards the mast when attaching the twist shackle to the sail.
If you need a new ring and shackle anyway, you might just want to get the Aussie ring instead (includes twist-shackle welded to the ring), and rig as Nick explained. Cost is probably pretty similar. I've never used one, but they supposedly make it much easier to hook/unhook the halyard.
Conesus Lake, NY
1976 Hobie 14