A reference sample is a garment that is similar in size and shape to the garment you are wanting to create. It is not used to replicate the garment you have, but to guide your designer on spec measurements, shape and fabric feel.
If you don’t have a reference sample that is ok, but it just means that you might run into more sample rounds than if you had one. Finding a reference sample is part of the research and development phase of the design process. Without reference samples, the tech packs might not reflect the correct specs and shape that you are after.
Design Handover + Reference Sample = Tech Pack!