Hey!

I am knitting a pair of booties.

Can someone please explain how I carry out a K1B in YF of previous row please?

Thanks.

Can you quote the two relevant lines of the pattern for us (not the entire pattern)? Just the row with the YF and the next row with the K1B?
A link to the pattern would also work.

That may be knit 1 through the back loop, not knit 1 below. Doing a ktbl in a YO will twist it closed so it's smaller.