Both will do. Annexes and proforma invoices of foreign exchange contracts, as an integral part of the contract, can be stamped separately or stamped with a riding seal. In economic activities, contracts often contain some contents, which need to be reflected in the form of annexes. This annex is an integral part of the contract. Without this attachment, the contract would be incomplete. Therefore, when stamping, the attachments of the contract should also be stamped together or stamped with the riding seal.