As Finman sorry FINSKY!!!! says (he does get around) trickling applied with a syringe 5ML per seam of bees.
If i used it
I would mix
1kg sugar with 1 litre warm water
TAKE THIS OUT SIDE!!!!! and whilst still warm(40C WHAT EVER THAT IS IN AMERICAN) mix in the crystals (35g) until completly disolved do'nt forget wear a suitable mask!!! and goggles and do not breath the steam/fumes.
For winter treatment(a brood less period is the ideal) the hives can be opened and 5ml is applied of the WARM mix between each frame/seam of bees. Oxalic is also good for treating packages/swarms/or shook swarms in cages. Mite drop can be checked by placing a card under the cage. OXALIC APPLIED IN THIS WAY DOES NOT KILL mites that are in cells.