I have a box of D163 back in the UK with instructions, I'll be back there in about 2 weeks. The small bag is the developing agents Part A, the larger bag the carbonate etc.
Mix the small bag first in about 75% of the water (whatever the box states it makes) then slowly add the second bag, stirring well, then top up to the final volume.
Use 1+3 for normal use, or 1+1 for slightly higher contrast.
It was also sold as a Universal developer for films, plates & papers, gives very grainy negatives, It was once the standard Kodak print developer in the UK rather than D72 Dektol which was more common in the US.
Ian