How to input 2 signals (RF & LO) to power detector?

if the schematic of my power detector only has one input lets say vin, how can i input 2 signal in namely LO and RF signals at the same point? is it possible to just use the vin or i need to add another input pin?

You cannot apply 2 signals simultaneously to power detector, use Spectrum Analyzer to see their powers.
Power detector can not discriminate the signals and you read erronously total power.

SP2T switch?