I associate "ruching" with a trim of gathered ruffles or pleats. Here the term seems to be used simply as an alternative for "edging."
The 4-row repeat produces a medium-wide garter stitch border with two rows of ladder eyelets running horizontally along the top and two staggered rows of large eyelets in the saw-tooth lower edge. Four stitches are adding in the first row and are maintained in the stitch count until they are bound off in the last row.
You can download the full-size chart, verbal instructions and notes here.
Up next: I have absolutely no idea. Making sense of this Victorian knitter's patterns is proving to be considerably more frustrating than those of the previous one. My apologies for the long delays in between posts.