Short answer: RTK is for state and local information and FOIA is for U.S. government information. RTK is also for records and meetings and FOIA is just for records.
Long answer: The New Hampshire Right-to-Know Law, RSA 91-A, gives public access to state and local records and meetings within N.H. The federal Freedom of Information Act, 5 U.S.C. sec. 552, gives public access to U.S. government records. There is no federal statute for public access to meetings similar to RSA 91-A.
It doesn’t matter whether the records are kept within our state boundaries. What matters is who has them. If a federal agency has them in an office in N.H., then FOIA applies. If a state or local agency has them, then the RTK Law applies.