Unwanted Ruffling in Circular Doily

I found an old pattern online for a circular knitted tablecloth. Pattern had been adapted from a doily pattern. I am using recommended needle size, U.S. 5, but different yarn. I am using Peaches 'n Cream from Wal-Mart, worsted weight cotton. Beginning at center and knitting outwards on two long circular needles (same technique as sock making). I completed first 36 rows. Work should more or less lie flat. It doesn’t. It ruffles–too much fullness. Found group of crocheters discussing this problem and discovered some of it may block out. I’m not sure of this; I’ve got way too much fullness. Double checked that I have right number of stitches and that I have not flubbed the pattern. Boy, howdy, do I need help/advice.

Does the pattern tell you how many sts you should have after each row? Maybe you’re increasing too many times in a row or increasing too many sts at each increase. Some of the fullness will block out but an error, especially early on might keep getting worse as the number of sts increases.
Can you quote a few lines from the beginning of the pattern or better yet, link to the pattern?

are you using the right needle size for the weight of yarn you’re using? If your needle is too small for the yarn that could be the problem.

I agree - usually when you get either a ruffle or binding in an old pattern the needle size is wrong for the yarn weight…

The needle used in the pattern may be a 5mm which is a US size 8, but since this should probably be loose and open, you ought to go up to a 9 or 10.

It may have been using heavy cotton crochet thread which would be the equivalent of sock yarn weight. A US 5 needle would be fine with that to make it open and lacey.

Another thing to consider is the age and source of this vintage pattern. Knitting needle sizes were different 50 years ago and beyond. It may have been written in old US sizes or in the UK. Then a UK size 5 would be an American 9. I question the use of that type of yarn. Doilies were popular in the 50’s and early 60’s. Every doily I ever saw was done with the thin mercerized crochet cotton balls. It was considered strange to knit or crochet doilies with yarn. It just wasn’t done. The proper size knitting needles for this cotton would be a 0-2.