An FSR (Force Sensing Resistor) varies in resistance as force or pressure is applied. Most often such devices are connected to the positive power rail and the ADC input of a embedded micro controller. At the same time a second known fixed resistor is connected to the opposite power rail (ground) and the same ADC input. This forms a resistor divider network where the ADC in the embedded micro controller can measure the force applied to the FSR by measuring the voltage of the resistor divider.
To measure 2 or more FSRs using the same ADC input, consider connecting one lead of each FSR to a digital input/output pin of the embedded micro controller. Then connecting the other lead of each FSR to the ADC input. To measure the force on the 1st FSR, configure the connected digital pin as a high ouput using software. So that all the other FSRs do not influence the measurement, configure all the other digital pins to have high impedance. Often this can be done by programming these other digital pins as inputs. Cycle through all FSRs in a similar fashion using software.