Calculating R1 and RFOD for BQ51050B
I recently used the bq51050b in a commercial project.  In section 9.2.1.2.3, Charging and Termination Current (on page 30), it says "Setting R\$_{FOD}\$ to 200 Ω as a starting point before the FOD calibration is recommended."  And then solving for R\$_{1}\$ using the equations in section 8.3.4.3, Battery Charge Current Setting Calculations on page 20.

So that's what I did, and ended up just using the 200 Ω value.  That is also the value that TI uses on their evaluation board for the charger (labeled R2 on page 3 of that PDF).