Welcome to the forum. You have 2 choices;
1. If you do NOT have a virtual folder, then you can use the file:/// protocol, eg.
Local path: c:\myfolder\docs
Virtual path: file:///c:/myfolder/docs
That will do the import, but you will find that unless you are indexing a UNC, the results will only work on your machine, because the links are specific to your local path.
2. Otherwise, it's better to use a HTTP virtual path when you can, eg.
Local path: c:\inetpub\wwwroot\sub\docs
Virtual path: http://localhost/sub/docs
Please let me know more about what you're doing and I can give more specific advice.
Best
Jim
-your feedback is helpful to other users, thank you!