I was hired by a member of a non-profit organization and during the contract process, I wasn't too sure if he should sign with his name or use his organization's name? I had him use the organization's name. What about the invoice? Whose name should be on it? Any one can maybe show some examples of their invoices?

e.g. Employer is John Smith. The non-profit organization he's in is Pet Coalition.

This is the invoice I have:

John Smith
Special Advisor
Pet Coalition
Street Address
City, State, Zip code