LTC1968: How do I calculate the capacitor value for AC Coupling?

I am using LTC1968, and I want to use a differential input since I have two sine wave input with frequency of 210kHz, and both are in-phase. I would like to know how to calculate the capacitor value for the input. The two sine wave input are from the same branch, and I am trying to use the idea of wheatstone bridge to reduce noise; therefore, I would like to do differential input. One of the input will have lower voltage compared to the other input by using potentiometer.

I hope to hear your response.

  

LTC1968 Datasheet: https://www.mouser.com/datasheet/2/609/1968f-1272086.pdf