Potbelly stove standing on hardwood floor directly
There are code requirements on this. NFPA 211 is the code section you probably are looking for. The stove will either be UL listed and certified and have specific clearance and hearth requirements mentioned in its installation manual or be unlisted. So when we consult the manual for the Vogelzang Cast Iron Pot Belly Stove, Model# PB65XL, this kind of leaps out at you.

THIS STOVE IS NOT A UL LISTED STOVE

Unlisted stoves start having all sorts of requirements like having a fire resistant hearth underneath that extends 18" out in all directions from the stove perimeter, 36" clearance from the wall unless heat shielding is installed. 

Sheet metal below the stove is not sufficient. 

The hearth has to be a material that can give you protection from the floor and underlying structure igniting, usually sheet metal over the top of masonry and the stove must be constructed such that the firebox is 6" or more above the surface.

So, returning to the manual for this stove, we find:


  The stove must be placed on solid concrete, solid masonry, or when
  installed on a combustible floor a solid surface floor protector
  listed to UL1618 Type 2 with a minimum of 1" thick and a R-value of
  3.0 or greater, such as Hy-C or Imperial Model UL 5463BK must be used. 
  
  (NOTE: To calculate R-values of equivalent alternative materials, see page 15).
  
  The base must extend at least 18" beyond the front, rear and sides of
  the stove, and must extend underneath and 2" beyond each side of
  horizontal connector pipe if it is elbowed towards a wall (see figure
  5 and consult local building codes and fire protection ordinances.




One such item that may fill the bill is the HY-C Floor Protector/Wall Board. 

HY-C Floor Protector Manual for installation.

If you decide to DIY your floor protector, it basically has to be usable as an open hearth (resist 2 hour burn) and consists of a 2" thick firebrick platform overlaid with 24ga. min thickness sheet steel that extends out 18" from all sides of the stove. It also has to extend under the pipe to the wall. 

Note: Depending on where you live, not properly installing a wood stove or not getting installation permits where required will void your home-owner's insurance where loss by fire started by the installation occurs.