It appears that IPAPPEND 2 is required when using ksdevice=bootif.

I recently installed two HP Proliant DL380e Servers with an integrated 4 port NIC having only port 1 wired. According to various documentation, Fedora, CentOS, RedHat this is required to allow the PXE'd NIC to be passed to the loaded installer kernel to avoid the network interface selection prompt.

The PXE Linux Template should look something like:

default linux
label linux
kernel boot/<whatever>-vmlinuz
ipappend 2
append initrd=boot/<whatever>-initrd.img ks=http://foreman.example.com:80/unattended/provision ksdevice=bootif network kssendmac