Size of resistor connect to positive input of an inverting op-amp (LMH6702)
When the opamp is in service, the voltage at the negative terminal will be at zero volts (a "virtual ground").  The idea of the 25-ohm resistor is to balance the small input bias current that is present on all op amps, so that the voltage generated by this current is equal at both terminals.

This can be accomplished by making the impedance at both terminals equal.  You have Rg + Rt to ground (3150 ohm) in parallel with Rf (237).  Therefore, the resistance should be 3150 || 237 or 220 ohm.

With your new values 3960 || 237 provides an answer of 223 ohms.  Choose the nearest standard value; it does not have to be exact and is only "best practice."  In actual practice, the resulting error from choosing a different value will be slight with a good op amp.