Tds on professional fee paid to nro account

If the service is received in india then u can follow relavant country dta rate / section 195 rate / 20% for not having pan whichever is lower in this case u have to obtain TRC certificate / pan of relevant country and declaration to the stating not having PE in india.
if services are rendered and consumed outside country itself then no tds will come

Sec 195 will applicable