Fuser-nsp-romslab.rar -

The .rar file is a container. Use a tool like or WinRAR to extract the contents.

Use a tool like DBI or Tinfoil on your Switch and a companion app like NS-USBloader on your PC to transfer the file directly over USB. This avoids the 4GB file size limit of FAT32 SD cards. FUSER-NSP-ROMSLAB.rar

Ensure your console has the latest sigpatches installed. Without these, the Switch will fail to launch custom NSPs. FUSER-NSP-ROMSLAB.rar