Pattern description from the Oat Couture website

This super-comfy (and super-easy!) shirt is knit in reverse stockinette stitch. The seams are on the outside for detail. The Silverlake Shirt can be casual or dressy depending on your choice of yarn.

Pattern may be knit in worsted or chunky weight yarn.

Yardage/needle requirements:
Materials,Worsted Weight
930 (995, 1095, 1165, 1260, 1325, 1440) yds 850 (910, 1000, 1065, 1152, 1211, 1316) m worsted weight yarn
Knitting needles sizes 6 & 8 (US) 4mm & 5mm
split-lock markers
Gauge: 20 sts, 26 rows = 4” 10cm in reverse stockinette st. with larger size needles
Materials,Chunky Weight
675 (735, 815, 865, 950, 995, 1075) yds 617 (672, 745, 790, 868, 910, 983) m, chunky weight yarn
Knitting needles sizes 9 & 101/2(US) 5.5mm & 6.5mm
split-lock markers
Gauge: 14 sts, 20 rows = 4” 10cm in reverse stockinette st. with larger size needles