Reference for the below knit kit:
If you stretch out your work like the below image, you will see bars between each knit and purl stitch on the ribbing.

Thread your end through the embroidery needle (a contrast yarn is used in the example below to make it easier to follow along).  Picking the nearest column of V stitches, bring your needle through every other bar.

Bringing your needle perpendicular, thread it under the nearest adjacent stitch.

Now, bring your needle down through every other bar of the purl stitches.

Repeat a few additional times to secure your end, then cut any remaining yarn.