Comment by tetris11

If anyone wants to try multiple kernels on their machine, here's how you'd do it with systemd-boot

    ## install mainline, bleeding, secure, stable, and stable realtime, mainline realtime
    pacman -S linux linux-zen linux-hardened linux-lts linux-rt-lts, linux-rt
    ## and I guess, soon to be: linux-rt

And then add the following 5 bootloader entries as separate files

    #/boot/loader/entries/linux{,-zen,-hardened,-lts,-rt-lts,-rt}.conf
    title Linux {Main,Zen,Hard,LTS,RT-LTS,RT}
    linux /vmlinuz-linux{,-zen,-hardened,-lts,-rt-lts,-rt}
    initrd /initramfs-linux{,-zen,-hardened,-lts,-rt-lts,-rt}.img
    options root=PARTUUID="the-part-uuid-of-your-root-partition" rw

and after those 5 files are in place, do a `bootctl update`