The Verticl Chain Stitch in smocking is nothing more than the Chain Stitch worked along the top ridge of the pleat.

You can combine the Vertical Chain Stitch with the Smocking Chain Stitch to create lovely designs in your smocking. Just be careful to adjust the stitch tension and stitch length accordingly when you switch from hiorizontal or diagonal stitching, when you are actually stitching through the pleat, and vertical stitching, when you are stitching along the pleat.

Notice that you may need to turn your fabric upside-down and work the Vertical Chain going up instead of down.