How to use the system Object comm.OFDMModulate to find the Bit Error Rate in a Rayleigh Fading channel?

if we have Modulation (e.g QPSK) Symbols and input sizes of data and pilot as [48 1] and [4 1] (which means 48 QPSK Symbols and 4 pilot symbols) respectively. Lets say we have Rayleigh channel values as (a+bi). Given these, how can we choose the values for pilot symbols and how can we pass the OFDM system object output through a Rayleigh fading channel and can get BER values for different SNR? I may not have clarify my question but if someone have done work with OFDM SystemObject in MATLAB please help.