Sec 68 gets attracted when any amount has been credited in your books for which the explanation offered by the assessee is not satisfactory in opinion of A.O.
However if in case of Pvt. Ltd. company if the amount credited consists of share application money, share capital, premium then it is deemed to be not satisfactory. Thus sec 68 will get attracted if any amount has been credited in books on account of share application money.
However, it is to be noted that such amount shall not be considered as Income of the assessee if he offers an explanation with regard to nature and source of share applicant and the explanation offered is satisfactory to the A.O.