Tolerance of the resistor doesn't matter (will be fixed with software).
Stability of the resistor/pot does. Best to use two fixed metalfilm resistors (no pot).
If you use 100k as top resistor, then the resistor could dissipate <=0.1watt.
1/8watt is borderline, both for power and maybe voltage (1/8watt is tiny).
Use common 0.4/0.5watt metalfilm.
Leo..