One thing I've noticed is that RTW pencil skirts are often way more pegged at the knee than any pattern I have come across. I think this is purely because it is much easier to take off than "let out" and the amount of pegging required does vary alot from person to person depending on the hip/waist/knee ratio or how much the hip area "sticks out". I really noticed this when sewing the Cake Patterns Hummingbird Skirt for myself and then later for my gorgeous plus sized cousin. When making it for myself it definitely needed pegging, it looked much better when I took the sides in from hip to hem about 2" overall, tapering it in for a more flattering shape. When making it for my cousin I just sewed it up "as-is" based on her measurements and when she tried it on the skirt was already perfectly pegged for her shape as is. It was an interesting observation that I filed away for future reference: what is not pegged on one shape is very pegged on another, it's all in the curves of the wearer.
I think this difference is a reason why there are so many pencil skirt patterns "out there" as women who sew strive to find a perfect pegged shape for our shape. We keep buying thinking "maybe this one will look better", but honestly, it is so easy to do and any straight skirt can be easily adjusted to give you the perfect amount to "vavoom" that works for you.
Aside of the dozens of online tutorials of varied and occasionally dubious quality for knit fabric pencil skirts, the very first pattern I saw online that was strongly pegged was the the By Hand London Charlotte, a pattern I have resisted buying as I already own several pencil skirt patterns which I had already adjusted to be more pegged, namely the BurdaStyle Jenny (made here and here) and the Gertie double darted pencil skirt from her first book, which you can see here and here.
A couple of very pegged knit pencil skirts on offer are the Colette patterns Mabel (which I don't own) and the lesser known but I feel more elegantly drafted with interesting design details the Wiggle Skirt by Iconic Patterns (which I do own and would love to make up soon).
|Pegging a pencil skirt. Click to enlarge|
Draw a straight line from the point on your hip where your curves start going back in (so, the bottom of your hip curve, as it starts to go back to your knee). Works great most of the time especially if your skirt is on the knee or above. Seen in the By Hand London Charlotte (from looking at google images online, the pattern artwork and these images here). For myself when I am at a heavier weight and therefore my waist/hip/knee curve is more dramatic, I find this method can result in an almost tulip shape.
Method Two (shown on the right).
Draw a straight line as above but when you get to to top of your knee, straighten the curve out for the final 3 to 4 inches/ 8 to 10 cm so that it is perpendicular to the hemline. Works well for below the knee skirts and prevents a tulip shape skirt if your line from hip to knee is a really strong angle. Seen in many RTW skirts, the Wiggle Skirt by Iconic Patterns. For myself, when I am at a lighter weight and my waist/hip/knee curve is not so dramatic, I find this method works really well and is how I adjusted the houndstooth skirt in these photos.
How much to peg.
I usually pin fit my skirt before sewing up the side seam. I usually find that I take in my skirt an additional half to a full inch at the side tapering up to nothing at the hip, which brings in the skirt a total of 2" to 4". I think the amount you bring it in is really personal and depends on what kind of material you are using, and what method you are going to use for walking ease such as a back vent, kick pleat or split. (The Iconic Patterns tutorials on skirt vents are a must read, including this one which is great to know if you like your skirts really pegged and don't want your vent sitting at an angle like below)
This skirt started off as a Gertie Skirt with a shaped waistband and ended up being completely recut and remade into a Jenny Skirt, underlined with organza to give the skirt more body and a bow at the back for fun. I didn't completely fix some issues I had with cutting both the left back panel and waistband front completely off grain (still don't know how I did it and only noticed it when I was taking the skirt in and ended up completely recutting and resewing the entire skirt) but it is much better and the vintage fabric was too precious to not try to recover.