Current Flow Line in HFSS

when I want to assign lumped RLC, HFSS asks for current flow line.
is it important? what is its functionality?
thanks.

It just define how +/- polarity of the potential drop across your lumped element. Whether it is crucial or not, that depends on the circuit that you are simulating. Ideally, makes the current welled into a ground plane.

hi
actually, lumped capacitor is not between feed and ground. think two microstrips, lumped cap is located between these two strips.
can you suggest any idea?