Probably not the response you want, but I don’t think restoring to a smaller drive works using this.
I’d personally suggest using a different application for the task, I believe both Acronis TrueImage or Macrium Reflect will work. Both offer free versions, I’ve used Reflect Free myself for the task in the past, simply cloning to the SSD with it hooked on by a USB adapter cable (they’re really cheap) then swapping out the drives.
Once migrated UrBackup will do nicely for ongoing backups.
There’s probably a workaround, but I doubt it’s as simple as my suggested approach.