We are currently working on an easier way to restore for self-managed backups for another machine. For now, you can use these instructions for restoring your antlets from self-managed storage.
1) Create an antlet with the same name and same type (LXC, KVM).
2) Go to the Backups tab.
3) Click on Backup Now.
4) Click on "Import Self-Managed Backup (Beta)"
5) Input the same parameters that you would like when creating self-managed backup. You can find the ID's in the external storage names.