Adding a Hang-Tab to Your Hat
If working brim-up: After finishing the crown decreases as described in your pattern, decrease further until there are only 4 stitches left on the needles if working with DK or finer, or 3 stitches if using yarn thicker than DK. Then switch to a smaller needle (at least 1mm smaller) and work an i-cord for approximately 6cm (or as preferred), bind off, and affix the tip of the i-cord to the main fabric, resulting in a loop.
If working tip-down: Start with needles at least 1mm smaller than your working needles, and work an i-cord (either a 4 stitch i-cord if working with DK or finer, or 3 stitches if using yarn thicker than DK) for approximately 6cm (or as preferred). Then switch to your working needle size, and increase stitches as needed to get the cast-on numbers in your pattern. Skip the cast-on instructions but otherwise proceed with the pattern as-written. At the end, affix the tip of the i-cord to the main fabric, resulting in a loop.
Hang tight and enjoy!