Because of the method the library chooses, resistor choice for the "R" of this circuit is key. The Arduino article on this library \cite{capacitivesensor} includes a nice list of resistor values and their corresponding effects on the circuit. As expected, larger resistors allow for more precision when measuring τ, but have the trade-off of higher read time. Fortunately, the read time we require for this circuit is large enough (200ms-500ms) where a greater increase in resistor value will not have an adverse effect on device function. Additionally, too large a resistor value (10MΩ - 40MΩ) gives us precision at distances where the other components in our sensor, including the second capacitance sensor, could affect the capacitance sensor measurement.