Edit your /etc/layman/layman.conf
#-----------------------------------------------------------
# URLs of the remote lists of overlays (one per line) or
# local overlay definitions
#
#overlays : http://www.gentoo.org/proj/en/overlays/repositories.xml
# http://dev.gentoo.org/~wrobel/layman/global-overlays.xml
# http://mydomain.org/my-layman-list.xml
# file:///var/lib/layman/my-list.xml
overlays : http://www.gentoo.org/proj/en/overlays/repositories.xml
https://raw.github.com/na4zagin3/proof-overlay/master/overlay.xml # add this line!