you are supposed to use polymer like Forton or a powdered admixture, not bonding agent which is different. bonding liquid is a concrete glue. But yes, follow guidelines although with slurry mixes the correct ratio isn't that important since you are just filling little holes.
For a general guideline we recommend using one part KongKrete liquid Acrylic Polymer (50% solids) to 4-5 parts water. Mix this up in a jug and use this for mixing slurry. The more polymer you use the more "plastic" your grout will be.
Be careful if using powder polymers...most are designed to re-wet and not ideal for a countertop that gets wet...
I would keep it simple and use something like Poly Blend non sand grout which has polymer in it.