“R = 68 kΩ” is recommended “from CLK_IN to GND” but there is no further recommendation regarding tolerance of the 68kΩ resistor and possible affects the variation of the Internal Oscillator.   
We have an application that may not tolerate a ±30% variation in PWM output clock.  

Does a 68.1k ±0.1% 25ppm resistor “from CLK_IN to GND” result in a tighter Internal Oscillator and a tighter PWM output clock than a 68k ±5% 200ppm resistor? 

Does changing the resistor “from CLK_IN to GND” to the next available fixed value (up to 69.8k or down to 66.5k), increase or decrease the Internal Oscillator frequency?  If so, how does the Internal Oscillator frequency change and what range resistor values are allowed?

Ultimately, we want a time cycle [tc] variation that is tight enough to create a PWM frequency that ideally varies by ±10% or less, if possible.