It's rare that any retail broker will allow stop loss orders in OTC, try it on this ticker let me know what your results are.
Besides, who would have any funds in OTC, and not be paying constant attention. No need for a stop order of any kind.
Disclaimer: Everything I post is opinion and is not to be taken as investment advice. You make your own decisions based on your own judgement. Do your own DD = 'Due Diligence' = Your trade, Your responsibility.