Because the pattern repeat is so wide, the easiest way to change sizes is by changing your gauge, in conjunction with adjusting the stitch count. Pattern is writen for gauges of 6/st in to 7.5 st/in, with circumferences of 16-26.75 inches.

Measure gauge in blocked colorwork pattern, using suggested needles, then reference size chart in pattern to choose size.

1 Skein Each: Nature Spun Sport by Brown Sheep Company (100% Wool; 184 yd 168m/50g)
MC: Ash (720S)
CC: Pewter Green (401S)

Kit available at MsCleaver.com