This more than you asked for, but . . .
Vin = 1.590 vdc, (D Cell)
The readings below are R measured, Voltage across component, measured, component resistance calculated.
Safety resistor: 99.9 Ohms, 0.526 Volts, 97.32 Ohms
Variable resistor: 161.4 Ohms, 0.868 Volts, 161.4 Ohms
Thevenin's Theorem suggests that the voltaage dropped across the meter is around 0.772 Volts.
This gives a calculated current through the whole thing of 5.377 mA based on the values for the variable resistor, which seems pretty stable.
If I base it on the safety resistor I get 5.31 mA. I've figured it three ways (Safety resistor, Variable resistor, Safety resistor + Variable resistor.) I get a slightly different set of values each time, but each one gives me a value of pretty close to 5.3 for Imeter, which is pretty much what it looked like to me, although I thought I was closer to an even 5 mA.