I'm sure this has been asked before but how do I type the dot between katakana words like ハリーポッター?

It's the backslash key in IME mode. Observe:

・・・・・・・・・

I'll have to be honest that I'm not exactly sure what IME mode is, but when I hit the backslash key in hiragana input mode it just types a backslash.

Forward slash.

Oh, dear. I'm so used to throwing around "backslash" in my day to day conversations that I said the wrong one. How embarrassing. :|

Haha, no problem at all Mcjon. Thanks for the quick response!