It looks like you have 15 st of ribbing before the marker. The M1 stitch needs to be made right before the marker and will be added to the ribbing on the rows after it. So…
Row 1: K1 (p1, K1) 7 times. Heres your increase: M1. Then slip the marker. Your increase ahould be on the rib side of the marker. Then continue the moss stitch pattern to the end of the row.
Row 2: work the moss stitch pattern to the marker. Slip marker. (K1, p1) 8 times
Row 3: (K1, p1) 8 times. Slip marker. Work moss stitch pattern to the end of the row.
Row 4: same as row 2.
This is where it gets complicated…row 5 will be another increase row similar to row 1. BUT when you come back on row 6, the stitch you created will be a purl stitch (to keep with the ribbing pattern) after the marker. Increases will be on rows 1, 5, 9, 13, etc until you have increased to 99 stitches. The added rib stitch will alternate between knit (rows 2, 10, 18, etc) and purl (rows 6, 14, 20, etc).
Please let me know if this helps. I don’t have any other knitters around to see if it makes sense to them. If I’ve further confused you, I apologize.