Can't run nixos-rebuild switch --flake

I was going to suggest a script like in #53 (closed), but I figured I'd share my experience so far.

No idea what's wrong here, but clearly I'm not doing it right... I change my hostname to rados in options.nix. I then run this command (quite possibly not understanding if this is correct): sudo nixos-rebuild switch --flake .#rados.nix

I then get this error:

error: flake 'git+file:///home/rad/zaneyos' does not provide attribute 'packages.x86_64-linux.nixosConfigurations."rados.nix".config.system.build.nixos-rebuild', 'legacyPackages.x86_64-linux.nixosConfigurations."rados.nix".config.system.build.nixos-rebuild' or 'nixosConfigurations."rados.nix".config.system.build.nixos-rebuild'