I would not bare-root, keep a bit of the original soil and mix it through the soil before potting the tree.
The dosage... hm. Let's assume it is 1/4 tablespoon for an average size and base the dosage on the relative size of your pot (and now the question is: what is an average size? )
"sprinkled onto roots during transplanting, worked into seed beds, blended into potting soil, “watered in” via existing irrigation systems, drenched into porous media, applied as a root dip or plug dip, or injected into the root zone of existing plants. The type of application depends upon the conditions and needs of the applicator, so growers can choose the application method that best fits into their current growing practices"
For me that would be blending it with the soil.
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