1. Contact relevant parties: If you know the identity information of the embezzler, you can try to contact the other party and ask the other party to stop using their signature. If you don't know the identity information of the embezzler, you can also try to contact each other through relevant institutions or organizations.
2. Seek legal help: If the above measures have no effect, then you can consider seeking legal help. You can consult your local court or lawyer to know your rights and feasible legal channels.