fixed from me and working
kernel tftp://${fog-ip}/os/redhat/r9/vmlinuz
initrd tftp://${fog-ip}/os/redhat/r9/initrd.img
imgargs vmlinuz initrd=initrd.img root=live:nfs://${fog-ip}:/images/os/redhat/r9/images/install.img ip=dhcp inst.repo=nfs:${fog-ip}:/images/os/redhat/r9/BaseOS splash quiet
boot || goto MENU