Import the signing key:
curl -s https://archlinux-lx2160.yxio.net/lx2160.gpg | sudo pacman-key --add - sudo pacman-key --lsign-key 612143A8503BD71E08A6976768E73A1FE6A4783B
Add to /etc/pacman.conf:
[lx2160] Server = https://archlinux-lx2160.yxio.net