Dear Sir,
Freight can be shown/charged in the invoice for movement of goods from factory to port and port to buyer's destination in a foreign country. If sale/transaction is based on CIF value the element freight is already included up to buyer's destination and if FOB basis, freight can be charged separately in the tax invoice.
Taxes and duties cannot be exported. As per Section 1(2) of IGST Act, jurisdiction of IGST Act extends to the whole of India. If GST is paid (through electronic ledger account) on the amount of freight incurred from port to the buyer's destination in a foreign country, ITC paid so cannot be encashed.