Dear Sir,
If you are a sole proprietor of your firm you can be a "PROPRIETOR"
If you are a partner in a partnership firm you can be a "PARTNER or MANAGING PARTNER'
If you are a Director and resolved in the board of directors meeting that you have been elected and declared as managing director of the pvt. limited company, you can be a MANAGING DIRECTOR.
In your case you have to be Managing Partner only.
Regards,
V.Ganesan