  The non-Hermitian systems with the non-Hermitian skin effect (NHSE) are very
sensitive to the imposed boundary conditions and lattice size, which leads to
size-dependent non-Hermitian skin effects. Here, we report the experimental
observation of NHSE with different boundary conditions and different lattice
size in a unidirectional hopping model based on a circuit platform. The circuit
admittance spectra and corresponding eigenstates are very sensitive to the
presence of the boundary. Meanwhile, our experimental results show how the
lattice size and boundary terms together affect the strength of NHSE.
Therefore, our electric circuit provides a good platform to observe
size-dependent boundary effects in non-Hermitian systems.
