It is 5 trc, all in the same st… so just writing it again here for convenience.
*sc in the next 2 sc ; “pop” st in the next sc* ;
rep *to* till last 2 sc ; sc in the last 2 sc. Turn
So I’ve attached my white yarn at the corner of Rectangle A, and sc in that same st ,
ch 1, sc in the corner st of Rectangle B ;
*ch 1, sc in the next st of Rectangle A ; ch 1, sc in the next st of Rectangle B* ;
rep *to* till you are at the last corner of your rectangle. Fasten off and weave in end.