This paper explores the effect of increasing number of receivers to evaluate the geographic location of the High Frequency (HF) transmitters for distances in the radius of 2000 km. In the case of HF propagation over long distances, signals propagate using skywaves and are reflected back to the earth from the ionosphere. The Quasi-Parabolic (QP) model of the ionosphere provides analytic equations for ray path parameters through which the signal travel time is obtained. The position of the transmitter is found using time domain HF geolocation method namely Time Difference of Arrival (TDoA). An analysis of the QP model of the ionosphere is provided and limits of the model are emphasized. The geolocation algorithm for TDoA along with its mathematical equation is explained. Simulation results demonstrate that increasing the number of receivers leads to a significant improvement in the geolocation accuracy.