Having trouble sewing neckline band onto metro neckline

Hello, I am really struggling with attaching the neckband to the metro t-shirt. I am using a knit fabric and a serger and am finding that the neckband doesn't stretch enough to fit around the neckline- when I tried making the neckband longer, it didn't lay right when I tried it on.The fabric I'm using has a fair amount of stretch. The edges of the fabric curl up, making pinning very challenging. Help!