Can I use BTRFS RAID with manual partitioning?

The problem is this, that I don’t know which module to add and how. I think that I would have to chroot after installation and add it.

ls /etc/modprobe.d/modprobe.conf
"/etc/modprobe.d/modprobe.conf": No such file or directory (os error 2)

Follows the text from here

Registration in /etc/fstab

If you don’t have an initrd, or your initrd doesn’t perform a btrfs device scan, you can still mount a multi-volume btrfs filesystem by passing all the devices in the filesystem explicitly to the mount command. A suitable /etc/fstab entry would be:

/dev/sdb /mnt btrfs device=/dev/sdb,device=/dev/sdc,device=/dev/sdd,device=/dev/sde 0 0

Using device is not recommended, as it is sensitive to device names changing that is affected by the order of discovery of the devices. You should really be using a initramfs. Most modern distributions will do this for you automatically if you install their own btrfs-progs package.

Using device=PARTUUID=... with GPT partition UUIDs would also work and be less fragile

Also talks here about modules

btrfs device scan is used to scan all of the block devices under /dev and probe for Btrfs volumes. This is required after loading the btrfs module if you’re running with more than one device in a filesystem.