You should get knit interfacing. You could also try a walking foot to allow all the layers to feed more evenly.

I agree with tuttlelady,and i also hope that when you cut it out,you cut it so the Stretch of the fabric goes Around her body.
Kathi

Hi Jon,
Agree with others about knit interfacing.
Did you pre wash the knit fabric?
You said finely knitted rib fabric, was it Ribbing or knit fabric there is a difference.
Are you using a needle in machine for knits?
Some knits if too thin or fine the facing may have worked better using a self bias method, adding a facing even with a knit interfacing may make it not fit or look correct.
Did not mean to overwhelm, just help, will check back in later.
Patti

Thanks for all of the help so far. To Patti's questions...

Yes, I prewashed.

After reading up on various types of knit fabrics, I believe mine is in the "interlock" category. It fits the description on the page linked below.

The needle is a "universal" type, recommended by the nice lady at the fabric store.

When you start talking about the "self-bias method," you're already over my head. That said, I think I probably used the wrong sort of interfacing. The lady at the store suggested one type, but I disregarded her advice because the stuff she suggested was not fusible, and the pattern instructions specified a fusible type. I think I probably bought a stiffer interfacing than was appropriate.

Here is a link that might be useful: Knit Fabrics: Types and how to sew them

Jon,
Read the link, interlock usually is a good weight, to work with.
It Also mentions the Ball Point Needles for the Knits.
Keep up the good work. Next time we will do the self bias.
LOL!!

Patti

None of my tee shirt patterns call for iron-on interfacing so I would be interested in seeing the pattern. Can you give us the number of the Burda pattern you are using?

One more thing. You will probably have more luck if you sew with the non-stretchy one on top. That way the feed dogs will do part of the easing for you and you shouldn't get too much stretching. Carol (who has made about 65 tee shirts this year, but I usually make ribbed necklines).

The knitted interfacing irons on & does not change the feel of the fabric very much. It stretches one way & doesn't the other. Put it on where it stretches like the fabric does. Don't move the iron around much attaching it...just pick it up & sit it back down until you have it attached to the whole area.

Thanks for the additional ideas. I haven't gotten back to the store for additional fabric, which means I also haven't made my second attempt yet. I'm certainly open to other methods of finishing the neckline, but a ribbed neckline is a no-go for my wife.

Carol, the pattern number is 3197. I did try sewing with the non-stretchy side up, but I found it made things worse because I couldn't see the wrinkles and pleats forming underneath, so I couldn't head them off at the pass.

Definitely use a ball-point needle so the knit won't "run" and use fusible knit interfacing. I find it useful to trim 5/8" off the edges of the interfacing so you won't have so much bulk sewn into the seams. I looked at the pattern. It looks like a good one, but I couldn't really see the facing too well. I would apply the interfacing to the facing, but that's just me.
Mary

I've made lots of t-shirts over the years with that type of neckline.I also buy ready made t's cut off the ribbing that's on them and they turn into a neckline very similar to that also.I can't stand anything up around my neck.

So here's what i do for both the store bough and the ones i make.I serge the edge,PRESS (not iron) turn in 1/4 to 1/2 " and top stitch.Works out great!!
Kathi

I recently started sewing knits also and found that a ball point needle was not enough, I had to go to a stretch needle. Also interlock knits sometimes have spandex or such that makes it more difficult. I had to loosen my tension a bit. I, too, on simple tops just turn the material under and stitch, then turn again and stitch again. This has worked for me. I do not have a serger, that would probably make such things easier.