Dear Shamjid

Four probe measurements are done for low resistance measurements to avoid contact resistance. However, when resistance is more than kOhms then four probe does not give good results. In that case two probe is the only choice. Is your resistance is more than Mohms then you have to take measurements in vacuum by mounting film in metallic sample holder for electromagnetic shielding. Substrate should be more resistive than film resistance. Feed through must be highly resistive. Shilded cable connections should be used. Measurements should be made in ohmic region. Once you measure current carefully at a particular voltage you will get resistance and then using geometry of the film you can get resistivity or conductivity.