We introduce a technique of RHEED ‘‘rocking patterns’’ for measuring rod intensity profiles and show that a simple kinematic interpretation may be used to deduce bulk structural parameters for a thin film. This method is used to identify a pseudohexagonal ‘‘1×1’’ epitaxial layer in the Ni/Si(111) system that is a precursor to single phase B‐type (twinned) or A‐type (untwinned) NiSi2. This material is a highly defective NiSi2overlayer which we call NiSi2(A/B). The possible influence of the reconstructed Si(111) 7×7 substrate in generating the NiSi2(A/B) structure is described.