HELP - Increase 1 stitch in 4x2 ribbing?

I am knitting my first sweater and after knitting a 4x2 rib pattern for 31 rows, the pattern tells me to “increase 1 stitch in the center of the last row”?

Does anyone know how to do this without breaking the rib pattern?

http://www.yarnspirations.com/patterns/long-weekend-knit-cardigan.html

I don’t think it will show since you’re not continuing in the same rib pattern. Just increase in the easiest place.