Which preposition to use with pleats

at Occurrences 1%

And she said, 'Is it?'and went on kind of pleating at her apron.

in Occurrences 1%

Its fashioning is quaint: the Watteau pleat in the back with tiny tucks each side at the slim waist line, the square low neck, the close elbow sleeves, the open front to display the quilted petticoat.

Which preposition to use with  pleats