There are all sorts of formulas for "Farmer's Reducer." Basically, you combine a ferricyanide solution with an hypo solution just before use. The classic Farmer's reducer is used for film, but a variation is very handy for prints. These formulas are from Kodak and are representative:
Kodak R-4a Farmer's cutting reducer for overexposed negatives
Stock solution A
Potassium ferricyanide 18.75 g
WTM 250 ml
Stock solution B
Sodium thiosulfate 240 g
WTM 1 l
Immediately before use, take 30 ml of Solution A, add 120 ml of Solution B, and add water to make 1 liter.
Place negative in working solution and watch carefully. Treat the negative for about 20 seconds; then rinse and examine. Repeat until the negative has reached sufficient reduction. When reduction is complete, wash negative for 5 minutes.
Kodak R-4b Farmer's proportional reducer for overdeveloped negatives
Solution A
Potassium ferricyanide 7.5 g
WTM 1 l
Solution B
Sodium thiosulfate 200 g
WTM 1 l
Place dry film in solution A for 1 to 5 minutes at 20C. Watch reduction carefully. Transfer film to solution B for 5 minutes, then wash. Repeat process as necessary.
Note: Can be used to reduce general fog by diluting solution A 1:1 with water.
Capacity: About 15 sheets.
I don't know where this came from, but it is an example of a variation for prints:
Farmer's reducer for prints
Stock Solution A
Potassium ferricyanide 64 g
Potassium bromide 30 g
WTM 250 ml
Stock Soultion B
Sodium thiosulfate 120 g
WTM 500 ml
For overall reduction, use 7.5 ml of Solution A, 180 ml of Solution B, and 1500 ml of water. Increase the amount of Solution A to speed up reduction.
For local reduction, use the same proportions as for overall reduction.
For spot reduction mix one part Solution A with 2 parts Solution B. Use undiluted.