A high Tc rf SQUID nondestructive evaluation (NDE) set-up has been realized to measure the eddy current induced field in different aluminum samples, under a weak AC and low frequency magnetic excitation. An efficient and simple analytic modeling method has been also developed for computing the magnetic field created by the induced eddy current in the samples and compare it with experimental results. The modeling results for different samples with various calibrated defects correlate well with the experimental data obtained with the rf SQUID gradiometers in an unshielded environment.