There are no roundhouse kicks in any shotokan kata, except for unsu, where there is a kick whilst laying on the floor which may be a roundhouse kick, or a side kick or even a thrusted front kick.
however, i believe there are no roundhouse kicks in karate kata because traditionally kicks were delivered low, maybe no higher than the knee. as a result roundhouse kicks seemed like a variety of sweep, which we do find in kata.
It is also interesting that a famouse instructor, (Sensei Kanazawa maybe, i will find out for you) tried to incorperate them into the kata Empi, so that following the rising punch and grap their was a roundhouse kick instead of hiza geri (knee)
check out my website to have a look at these kata, unsu in particular and make your mind up if its a round kick. I've got footage of a world champion, a european and a british and commonwealth champion all performing this kata, so you can watch the best.
www.karateonline.org
gary