Hi,
Please follow me:
1) Create an 2D-rectangular object in any where that you want to place resistor, exactlly such as a CHIP resistor .
2) In boundary assignment menu, choose Lumped resistor and assign your object to this, in this way you must specify your resistor value (100 ohm).
3) You must define a line form Top of object to Bottom as current line.
Need some help about resistors in HFSS. i want to use Flange type resistors in my power divider so how should go with that & how the connection between resistors & impedance lines built up in hfss???