In this paper, we present a model for the imaging process in tapping mode scanning force microscopy on liquid surfaces. The distortions induced by the imaging process can be calculated from measurements of the tip's oscillation characteristics. Furthermore, the momentum transfer and the average force acting on the liquid during imaging can be calculated from the measured quantities as well. Both the achieved lateral resolutions and the measured shifts of the tip's resonance frequency agree with the model. Any liquid-tip combination can be modelled and the feasibility of high-resolution imaging (lateral resolution < 10 nm) can be predicted. The predictions are confirmed by results reported so far in this field.