It all depends on the work that has been entrusted to the 'director' in your organization. If he is just a signatory to the documents, he need not be given any employment letter etc nor the question arises of him/her joining the EPF. As rightly informed by one of the members earlier, if the director is a salaried employee, all the other rules have to be followed.
Also make sure that the KYC of the director is done as per the new rule of MCA [Ministry of Corporate Affairs] else the DIN of the director will be deactivated.
Thanks and Regards
19th September 2018 From India, Hyderabad