what is the use - do you need "live" control of ratio during sim or just a setable/steppable ratio?
for the latter just use the parametric value defintion for a pair of R with the curly braces, and a .param for the setting variable
R1 value = {10k*(1-a)}
R2 value = {10k*a}
with a spice directive like one of:
.step param a list .1 .3 .6 .9
.param a = .5
you can even draw a rectangle around the R pair if you like it pretty - without needing .asy, worrying about lib management