New Hampshire Retirement System, Concord, is considering hiring one to three additional venture capital managers to handle a total of $50 million for the $5 billion plan. The money has been allocated to the asset class but not yet placed with a manager, according to Ed Theobald, chairman of the board of trustees. Potential candidates will be approached by consultant Evaluation Associates. A decision is expected in August. Currently, the plan has 30 venture capital managers handling a total of $200 million.