Need help with "Tudora" please!

I am working on finishing “Tudora” from the new Knitty and need help with it. I got Row 7 which reads:
Row 7 (WS): K6, BO 3 sts, k to end.
I need help here:
Row 8 (RS): K6, CO 3 sts, k to end (15 sts).
I don’t know what kind of cast on I should do here. I tried doing a cable cast on and it left yarn running through the button hole, if that makes sense. What kind of cast on would leave a “clean” button hole?

Thanks!

I usually use a knit cast on. Best of luck to you!

Thank you. Is that the “Knitting On” cast on method?

I always just use a backward loop cast on for two row buttonholes. Just fold the working yarn back on itself so that it forms a cursive e, then stick the loop on the right hand needle making sure that you really formed a loop and that it doesn’t just fall off, not having formed a loop.

Thank you - I will give that a try!