In the Wikipedia page there’s this formula
Just plug in values for the fence voltage and led. You can just set vswitch to 0 and Vled to 2V. It should be fairly insignificant compared to the fence voltage. It should be 10-20mA (0.01-0.02) to not kill the led.
The root of this is Ohms law: V=IR. Diodes cause a voltage drop rather than directly acting like a resistor which is why it’s subtracted from the input voltage.
Just put them in series. Make 2x, one in each direction to account for AC and DC
Sounds more like she was fired for revealing they pay an unlivable wage