Perform REST API for notes to supplier object when creating an attachment in requisition

Is there a way to perform REST API for "Notes to Supplier" when creating an attachment in Requisition. Currently, I can see the "Create one header - POST" to perform the creating an attachment in Purchase Requisitions but on the example, the "Notes to Supplier" only contains "NULL". The client wants to fille the Notes to Supplier during the creation of Purchase Requisition.