From How NTFS reserves space for its Master File Table (MFT) where it mentions a nearly identical (and identically functioning) registry key at the very bottom of the page:
Note This is a run-time parameter and does not affect the actual format of a volume. Rather, it affects the way NTFS allocates space on all volumes on a given system. Therefore, to be completely effective, the parameter must be in effect from the time that a volume is formatted and throughout the life of the volume. If the registry parameter is adjusted downward or removed, the MFT zone will be reduced accordingly, but this will not have any affect on MFT space already allocated and used.
The parameter simply attempts to ensure that the area after the MFT is kept clear for new entries in the event that the MFT needs to grow. It is essentially an indicator to the system that says "the user reckons they'll have millions of files and we will need MFT entries for a lot more than usual".
It is not a parameter that can be used to increase the MFT size per disk partition.
They do list the command
dir /a $mft to show the actual MFT size, but it does not work for me. Edit(by saultube 28): because it's for NT 4.0 which is pre-Windows 2000.
Microsoft do have a tool to show NTFS information per drive NTFSInfo and it will apparently show MFT size.
NTFSInfo will tell you where on the disk the MFT-Zone is located and what percentage of the drive is reserved for it.
In order to simply expand the MFT you can create a massive tree of folders which will use up entries in the MFT forcing it to allocate a new block. Done on an otherwise empty drive this will quickly expand the MFT without actually putting any significant data on the drive. The folders can then be deleted.
There is a tool to do this at Schooltechnician.co.uk: Increasing the size of your MFT but I make no claims about the tool, I am not affiliated and this is simply one I found at a quick search.
Per that page:
In my work, I have servers which hold millions of tiny files. I needed to have a large Master File Table from the outset to prevent future problems. I’ve created a free .Net application that will create a hierarchy of nested folders on a drive, and delete them again when finished. Creating folders seems is the easiest method of artificially causing the Master File Table to grow. Each folder seems to creates a 1024kb entry (1GB of MFT = 1,024,000 folders or files).