The yarn type, hook size, and gauge are very important for this pattern. Even a slight change can result in a hat that is huge.
Ravelry has had these yarns weights listed incorrectly. They can easily be verified by going to the company websites.
Main colour: Paca Peds, colour - Fireside
Weight - (2) Fine
Approx. 100g (360y)
Contrast colour: Herrschner’s Sock Yarn Stripes, colour - Aztec
Weight - (1) Super Fine
Approx. 50g (220y)
Skill Level: Intermediate to Advanced
Finished Size: 21" to 23" circumference
This pattern was tested, but really would benefit by having a chart. If you need a chart to complete these types of projects, maybe this isn't the best pattern for you right now. I hope to add a chart when I am able.