How to backup registry key

I’m trying to back up my registry key using the command prompt. I have read through the parameters and have looked at the examples (at https://technet.microsoft.com/en-us/library/cc742083.aspx), but can’t seem to get it right. Can anyone let me know what I’m doing wrong? Here’s what I have so far.

Wbadmin Start Backup –backupTarget:f: -include:c:\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsHKEY

I know this is wrong, and certainly the command prompt tells me that it’s wrong. What would I type to properly back up the registry key? It is located at HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsHKEY

Thanks for the help.