ok I just thought of this:
first step: A + B <-> AB
rate determining step: A + AB -> AAB
third step: B + AAB -> final products
I guess it's plausible as a simple example
I experimentally determined the reaction rate of the following reaction:
4HCl(aq) + 4NaS2O3(aq) -> 4NaCl(aq) + 3S(s) + 5SO2(aq) + 2H2O(l)
and found that the rate was proportional to [NaS2O3]^1 and [HCl]^2
I know that it's probably too tricky to determine the reaction mechanism or rate...