You'll probably be OK, but if you don't get carbonation after 4 weeks, at least you'll know why. If you ever have to add yeast at bottling, you only need a little. A half vial or dry pack into the bottling bucket should be plenty. You don't need to use the same strain, per se, but I would keep it as close as is conveniently possible and in dry form for cost. The little amounts of sugars fermented during carbonation is minimal enough to not notice a difference as long as it's not a strain that's way off to the style of beer. If you had to add it to the bottle, you could get a dry lager yeast and a pair of sanitized tweezers and add a "grain" or two per bottle, then recap.