Here are a couple feet that are sisters! (Cut from the same metal you might say!) ...and I've used them alot over the years. Both are types of traditional couching feet, several of many that Bernina makes. The #25 has five grooves or sections, so it will hold up to five threads and Foot #22 has three sections or grooves. I use the thicker threads like Razzle Dazzle or Candlelight, but any thread with that type of thickness will work beautifully!Each foot has a "gate" which closes over the top of the cords once you've inserted them into the foot, through each of the side escapes built into the foot. See picture below:
I like to use a serpentine stitch which is Stitch #4 on many Bernina machines. It's highlighted in blue on my machine in the picture below. The default setting of the stitch is 5.5 mm wide and approximately .5 in length. I like to adjust the length to at least a 1.5 or a bit longer to keep it feeding and moving along.
Here's the silver Razzle Dazzle thread, loaded into the foot, and the beginnings of the couching technique. You want to keep a firm hold on the threads, and let the little grooves do the work of separating the threads for you!
The pic to the right is a detail from the art journal quilt "Grace."
You can see my stitch length has been adjusted to a 1.70 in this picture; that works great too. It's a personal preference and so take a few minutes to see what you like best!
Hint #1: Make a test on a piece of muslin, and mark your settings down with a Sharpie marker for future reference.
Hint #2: Don't limit yourself to just the serpentine stitch! Try other utility stitches, or an 'open' styled decorative stitch too! Keep in mind that the less 'backward' movement a decorative or utility stitch makes, the better looking (and easier) it will be to accomplish your couching feature.
Here's another detail or view from "Grace" after I finished the little bit of thread accents added with this foot and the silver thread.I added this picture, as I am hoping you will be able to see the serpentine stitch on top of the thick silver threads. I like this look ALOT!
.... and I hope you will TRY IT, too!
Blessings to you all. EnJOY!