It depends on your expectation on luminance intensity of finished product. The dosage ratio of photoluminescent pigment to medium will depend on how much glow desired, your cost budget, market positioning, application method, medium type, pigment type, etc. A general guideline shows that rates 5% to 20% by weight are all OK.
In a simple word, a lower dosage rate and a more economic pigment grade will be better if the target market is at low-end side, in which a lower price is more important and the cost budget is more strict and tight. Anyway, experimentation will be the best method to determine the dosage ratio.