Help with Rib rows and patt2tog please

Hi all. I’m hoping for your help. I’m new to knitting since childhood and am knitting some cushions. I have completed one with some mistakes and I know where I went wrong except for on thing which appears in the next two cushion patterns so I’m hoping you can help please.

The pattern has me knit a rib section then a pattern section then a rib section to finish. On the finish rib section I have this:

Work 4 rows in rib starting with k. There are 81 stitches so I end with a knit stitch row one. Row two starts and ends with purl and then I do another two of these rows to make four.

And I’m on the right side of the work now

Then it says:
Rib 12 ( which starts with knit and the last stitch is purl)
Patt2tog (I’m guessing this is knit two stitches together but should it be a knit stitch which is the knit stitch or a purl which is the second of the two together?)
Yfwd (which I think is the yard in the knit position)
Then pattern 16 ( which I assume is rib, first stitch is knit)
And continue until 13 stitches left which are done in rib.

My query is that the next rows are 5 in rib and then cast off but how do I treat the stitches that are not k,p,k,p on the other side because I have put two together so I either get 2 p or 2 k together every 16 stitches?

I hope this makes sense. I just don’t think it looks right and I’m not sure what it’s supposed to be.

I’m hiding this bad rib section inside the finished cushion but that doesn’t seem right.

Thank you so much. Sorry this is so long!

Welcome to KnittingHelp
There’s a nice video that explains how to work these decreases so that either a knit or a purl stitch is on top when you work the decrease. It may be more than you want to know but it gives you some of the alternatives for very neat decrease lines. It uses 2x2 rib but the idea is similar.

The yarn forward in your pattern is a yarn over. It’ll keep the stitch count the same after the patt2tog. Bring the yarn to the front between the needles, then over the right needle to the back to work the next stitch. If the next stitch is a purl, bring the yarn over to the back then around the needle to the front again in order to purl. Either way, a single loop is created on the right needle.