The Triple Feather Stitch can be adapted to smocking very easily, just as the regular Feather Stitch.

Follow the same instructions as for the Feather Stitch, but instead of entering and exiting the pleats 1/3 and 2/3 of the way down the pleating row, divide the row into fifths. That is, the first stitch lies in the top 2/5 of the row, the second between 1/5 and 3/5, the third between 2/5 and 4/5, and the fourth in the bottom 2/5 of the row. This way, four feather stitches instead of two lie between the pleating rows.