Yes, that's the whole point. You want to make the new rib an intergral load bearer with the rest of the hull. As such, it ought to be fastened at each point, not only into the keelson, but also the beam shelf and at each point along the rib at each plank. If the planking has already had screws through it, it would be best if you moved the new rib along slightly to get fresher timber.
Remember that the strength of a wooden hull is the sum of its parts and no one part should take any excessive load.