If your Caste doesn't have its place in the Central OBC List, at All India Level, you should select General Category as your Category. But when you are filling Karnataka State NEET Counselling form, you can select OBC as your Category and avail OBC Benefits. NTA will open its correction window from January 15th to January 31st and during this period you can change your Category. And you will have to participate in All India Counselling under General Category.