A: No. An .rdr file is a proprietary disk image created by R-Drive Image and cannot be opened by standard macOS tools like Disk Utility or simply by double-clicking. You must use the R-Drive Image software (or its bootable environment) to read or restore it.
Your best path forward depends entirely on your goal: download macos high sierra 10.13.5 image file -.rdr-
A destination storage drive (Internal SSD/HDD or an external USB flash drive of at least 16GB). Your best path forward depends entirely on your
And your Mac restarts not into Recovery, not into macOS, but into a black screen with a single blinking cursor in the top-left corner. not into macOS
If you need to reinstall the version of macOS that originally came with your Mac (or the closest version still available), you can use the built-in Recovery system:
Transitions flash and SSD-based storage architectures to an optimized system featuring crash protection, strong native encryption, and faster directory sizing.