Andrew R Stewart 

In the shops I've been in we placed the reaction (anti rotation) washers either inside of outside the drop outs to match the drop out spread. The vast majority of production bikers that used SA AWs have some variation, from "perfection" in rear width. Only when the amount of remaining axle outside of the drop out prevented the reaction and the standard axle washers would I use reaction washers as the common outside of drop out axle washer under the nut.

BTW there are at least two rather different reaction washers out there. One is a stamped item with a bent tab engaging the slot. The other is a cast looking item with two flats spanning the washer's drop out face and having a series of sharp topped ridges which are meant to further bite the drop out to prevent slippage. These second ones I usually use outside the drop out if possible. Andy