Service tax on import of services

Textile designs are purchased from USA and the amount is paid as 5% of the PO of the export invoice of goods manufactured using that designs. IF it is treated as designing charges will it attract service tax or if I call it as Purchase of designs will it attract service tax.

or will the ST exempted under reverse charge as the services are performed in a non-taxable territory for a person in taxable territory.

Kindly advice.