There are many ways of hand sewing pencil pleat curtains. I'll show you one of them here.
My preference is for this method where literal 'pencil pleats' are formed. This produces a very robust heading where the drape fabric is locked in place and cannot move. It is suitable for drapes which are just lined, and also for ones which include interlining as well.
This method of hand sewing pencil pleat curtains is not well known, but produces great results.
You'll need a pencil shaped piece of wood, about 7" or 8" long (18-20cms) and about ½" diameter (1.2cms). The standard heading uses a 1" (2.5cm) wide drapery tape. You can use this heading for all drapery which has top treatments.
Cut a piece of 1" (2.5cm) drapery tape to the width of your required heading. Lay the tape on your table (front side down). Divide the tape up evenly into sections so each section is about 6" wide (15.0cms). Make sure there are an even number of sections. Mark each section.
(The easiest way to do this is to keep folding the tape into halves and mark each half.)
Lay the top of the drape onto the tape (drape front side up). Pin the two sides in position on the tape (B and C). Find the center of the drape and pin it on the center mark on the tape (A to D).
Now repeat this process for all the other sections.
So B is halfway between A and D, and C is halfway between B and D.
This process you have completed will ensure that the fullness is divided equally along the tape.
Insert the 'pencil' into one end of the heading. Turn the fabric over the 'pencil' so a pleat is formed. Using a strong thread sew the tape to each pleat, taking a small slip stitch through to the heading at the top of the tape.
This will require some judgment on your part. If you have more than double fullness in your drapes, then the pleats will need to be slightly looser than if you have less fullness. Working in small sections such as 6" allows you to gauge how to form the pleats so they are equal across the section you're working on.
When you come to the end, repeat the process along the bottom of the tape. Hand sewing drapery headings using this method gives a strong and robust heading. The fabric stays in position on the tape and doesn't 'bunch up' as can happen when tapes are machined on.
It's important to keep the 'pencil' at right angles to the top of the heading. There is always a tendency to slightly slant the pleats as you work. A right handed person will slant them one way, and a left handed person the other.
Once you become familiar with this method of making pencil pleat curtains you'll probably find you don't need to divide the panel onto the drapery tape. Or at least not into so many sections. With practice you'll know instinctively how to form the pleats.
This method of hand sewing pencil pleat curtains is very useful if you want to have pencil pleats on longer drapes. If your drape headings will be seen because you are hanging them from tracks or poles without a top treatment, they look better with deeper headings.
Just use a deeper drapery tape, and use exactly the same process. Instead of having a second row of stitches 1" down, you can have two or three extra rows spaced appropriately. So if your heading is to be 6" deep, your other rows of stitches will be set down just under 2", 4" and 6".
Many people have found that once they get used to using this way of hand sewing drapery headings they don't use any other method. It gives a long lasting finish, and works with all types of drape construction.