This paper explains a resistive nonvolatile memory (RRAM)-based physical unclonable function (PUF). The proposed PUF involves more variations and enhances the randomness by using four 1T1R cells to generate one-bit random data. Moreover, we propose a configurable replica column scheme and a biased current sensing amplifier to further improve the randomness. The proposed RRAM PUF is designed in 40nm CMOS technology. The simulated RRAM PUF with configurable replica columns achieves the randomness of 0.5001 with σ of 0.005. It also has a hamming distance of 0.486 over various responses for a single chip and 0.498 between different chips.