Phase-only beamforming is used in radar and communication systems due to its certain advantages. Antenna selection becomes an important problem as the number of antennas becomes larger than the number of transmit-receive chains. In this paper, discrete single group multicast transmit phase-only beamformer design with antenna subset selection is considered. The problem is converted into linear form and solved efficiently by using mixed integer linear programming to find the optimum subset of antennas and beamformer coefficients. Several simulations are done and it is shown that the proposed approach is an effective and efficient method of subarray transmit beamformer design.