After much contemplation about how to add the runes to Zelda's bodice, not to mention my lack of drawing skills, I found the solution that best suits me. If any of you can draw straight and evenly, based on what you see, I highly suggest doing that instead, since my method involves soaking the garment in water.
What I did was print off runes, in which I made using Adobe Illustrator. (Each rune is approximately 1/2" wide.) I then traced them, using a black permanent marker, onto clear water soluble interfacing and pinned them onto the overlay. Once pinned, I hand-embroidered over each using pearly white embroidery floss. After some practice stitches, I noticed 6 threads made the runes look too buky, so I unraveled 2 threads from it (using 4 threads). Doing so gave them a much smoother appearance.
Once the runes were embroidered over the clear film, I submerged it in water to disolve the film. To be honest, I really didn't like the effect the water had on my expensive silk fabric. It made it look wrinkly and feel rough, even with ironing. I found that mixing fabric softener with the water helped soften it, but the the wrinkles are still there.
I imagine any other fabric, such as satin, ployester and other cotton blends, would work better with this method. But it's too late to start all over now. I'll press on with the rest of them.