Kodak DK-25R is used to replenish D-23.
Water 125F or 52C - 750.0 cc
Metol (Kodak Elon Dev Agent) - 10.0 g
Sodium Sulfite, dessicated - 100.0 g
Sodium Metaborate (Kodalk) - 20.0 g
Add cold water to make 1.0 litre
Use 3/4 ounce of replenisher for every 80 square inches, discarding some developer if necessary.
(Taken from Amphoto's 1972 Black/White Processing DATA BOOK)