They shall have been for at least two years
residents of the district for which they are appointed, one of whom shall be designated by said board as chairman of the board of directors of the Federal reserve bank and as "Federal reserve agent." He shall be a person of tested banking experience, and in addition to his duties as chairman of the board of directors of the Federal reserve bank he shall be required to maintain, under regulations to be established by the Board of Governors of the Federal Reserve System, a local office of said board on the premises of the Federal reserve bank.