Yes, but I really wouldn't. It is getting harder and harder to access the registry (for good reasons - it was badly abused), and large values (as CSV files tend to be) aren't a good idea at the best of times.
Instead, why not store the file somewhere a bit more normal, and more likely to be backed up? Where should I store my data?
] makes some suggestions, and it's a lot easier to play with.
If you must store it in the registry, then see here: http://www.c-sharpcorner.com/uploadfile/puranindia/the-windows-registry-in-C-Sharp/