Archlinux, Manjaro, Antergos (AUR):
yaourt -S papirus-icon-theme-kde
Kubuntu:
sudo add-apt-repository ppa:varlesh-l/papirus-pack
sudo apt-get update
#Kubuntu 14.04
sudo apt-get install papirus-pack-kde4
#Kubuntu 16.04
sudo apt-get install papirus-pack-kde5