Kenneth L. Peoples, acting president and chief executive officer of the Farm Credit System Assistance Board, was named to that post Thursday by Agriculture Secretary Clayton Yeutter. Peoples had been general counsel and corporate secretary to the board before being named to the acting posts Aug. 15. Yeutter is its chairman. The board is a government corporation created by Congress in 1987 to provide help to the Farm Credit System, a farmer-owned network of cooperative lenders. Yeutter also announced the appointment of Kathleen M. Mullarkey as general counsel and corporate secretary. She had been acting in that capacity since Aug. 15. Before that, she was deputy general counsel to the board.