There are two things to bear in mind about the chief pointing out a rare collectible. First, although the TC does point in the general direction of the orchard, the collectible can be anywhere on the map. Second, the rare collectible may be one you already have, in which case you'll get 1500 tech points. If your game is well advanced you might not notice the addition of the points. It doesn't have to be a new one. I'm waiting on one rare collectible each for turtle shells, feathers and coral and I've used the Chief three times so far in the hope of finding them, but each time he's pointed out a duplicate.