  In the present article we investigate the influence of the contact region on
the distribution of the chemical potential in integer quantum Hall samples, as
well as the longitudinal and Hall resistance as a function of the magnetic
field. First we use a standard quantum Hall sample geometry and analyse the
influence of the length of the leads where current enters/leaves the sample and
the ratio of the contact width to the width of these leads. Furthermore we
investigate potential barriers in the current injecting leads and the
measurement arms in order to simulate non-ideal contacts. Second we simulate
nonlocal quantum Hall samples with applied gating voltage at the metallic
contacts. For such samples it has been found experimentally that both the
longitudinal and Hall resistance as a function of the magnetic field can change
significantly. Using the nonequilibrium network model we are able to reproduce
most qualitative features of the experiments.
