Okay, I had a little more time now to look into the Humboldt nutes than I had earlier this morning. The A & B should be used together, varying the concentrations of each depending on what point in the grow cycle the plants are in. During veg, them recommend 2 parts A to 1 part B, so a full strength feeding would be 1 ml A, .5 ml B to a liter/gallon. During flower it's 2 ml A and 2 ml B for full strength. Since your plants have finished their veg cycle I would recommend giving them 1 ml A and 1 ml B and see how they like it. If they react well, then increase it after a couple feedings to 1.5 ml A and 1.5 ml B. Autos are a bit nutrient sensitive, so you may not be able to go to full strength.