As per DTAA between India & China, the rate of tax to be deducted at sources is 10% for royalty. As per rates prescribed u/s 195 of Income Tax Act, 1961, the rate is 10% for both company & non-company deductees.
Since, the rates are same, tax rate to be applied is 10%. Otherwise, rate whichever is less must be applied. In this case, 10% + education cess @ 3%, i.e., 10.3% must be used.
The PAN of the deductee must be quoted in the e-TDS returns by asking them only. If PAN is not quoted in ETDS returns, then tax must be deducted @ 20%.
On the date of certifying the payment in Form 15CB, the exchange rates can be used. This exchange rates can be used for both TDS deduction & remittance of balance amount.