The DMX+RDM receiver chip IS3720 allows you to configure your own RDM Manufacturer ID; but how do you obtain this ID code?
The Manufacturer ID codes are assigned by the ESTA, you should apply for a Manufacturer ID code at ESTA:
https://tsp.esta.org/tsp/working_groups/CP/mfctrIDs.php
Manufacturer IDs 7FF0h through 7FFFh are reserved for prototyping and experimental use while a manufacturer is waiting for an assigned Manufacturer ID. They are not permitted in commercial products.