Need help on where to put this script.

[trevius]

LOL, the script example I gave above just happens to be related to handling player race sizes. So, you should be able to use the array from that script and set the size of the NPC with something like this:

%RaceSizes = (
	1 => 6, # Human
	2 => 8, # Barbarian
	3 => 6, # Erudite
	4 => 5, # Wood Elf
	5 => 5, # High Elf
	6 => 5, # Dark Elf
	7 => 5, # Half Elf
	8 => 4, # Dwarf
	9 => 9, # Troll
	10 => 9, # Ogre
	11 => 3, # Halfling
	12 => 3, # Gnome
	128 => 6, # Iksar
	130 => 6, # Vah Shir
	330 => 5, # Froglok
	522 => 6, # Drakkin
);

$npc->ChangeSize($RaceSizes{$randomrace});

Of course, you would need to do that after you set the $randomrace variable.