Hello !!

No,It isn't possible for you to claim reservation during documents verification if you didn't put it while filling your form.As,the seats in any institutions is fixed in reservation norms how much for whom.

So,sorry for that one but one probability also made in case if you want to claim reservation then approach to higher authorities for that if they are ready to grant your silly mistake then you are eligible to claim the reservation.

Hope this will help you.......