It was pointed out in a previous paper [Okitsu et al. (2006), Acta Cryst. A62, 237-244] that an n-beam Takagi-Taupin (T-T) equation can be solved for a crystal of arbitrary shape. The procedure to integrate the n-beam T-T equation is to let all the Fourier coefficients of the electric susceptibility be zero at positions inside the Borrmann pyramid but outside the crystal. The efficiency of this simple procedure is verified in the present paper by showing qualitative and quantitative agreements between experimentally obtained and computer-simulated X-ray six-beam pinhole topographs for a channel-cut silicon crystal.