🚀 go-pugleaf

I wish to use a 32KHz tuning fork crystal with an 68HC705 microcontroller.
Does anyone know the appropriate values for R and C in the oscillator circuit?

                | XXX |
  OSC1 ----+----| XXX |----+---- OSC2
           |    | XXX |    |
           |               |
           +---/\/\/\/\/---+
           |       R       |
          _|_             _|_
       C  ___             ___  C
           |               |
           +-------+-------+
                   |
                 __|__
                  ___
                   _
          
I don't have a data sheet from the Xtal manufacturer, and the values that
I use with a 2MHz or 4MHz crystal don't work.

The microcontroller I use is spec'ed to run with a crystal from 100KHz to 4MHz,
but works on an arbitrarily slow external clock.
Is there some fundamental reason for the manufacturer's 100KHz minimum?