Very smart to use a simple canvas bag as lining. The beautiful crochet stitch is clearly visible due to the contrast of the pink yarn on the white fabric. The canvas bag will also prevent your bag from stretching out. The bag is made with lace weight cotton yarn and a 3.5 mm crochet hook.
You can find the free crochet pattern of the Rose Tote on the website of KT and the Squid.