Jase, F is the catch-all for UTS' various fail codes (Z for outright fail, X for final-exam fail, others for other fails).
A fail DOES count towards your GPA, because it indicates failure to reach a certain level of competency over a given time. Fails totally demolish what may have been a perfect GPA (reducing the coveted perfect HD streak 7.0 to a mere Credit average). Avoid failing at all costs, even if it means begging for a CP - at least then you have a few points for the subject, you don't have to repeat it, and you don't have to pay again.
Edit: Sorry, I just realised I didn't even explain why fails count. You see, since you fail a subject you don't do well enough in that subject to receive any recognition - you have not earned the award. However, the subject still appears on your academic transcript (since you still studied the subject and attempted the exam). The GPA is a calculation of your average performance across all subjects appearing in your academic transcript (except in specifically defined cases - check with your faculty). Thus your performance in four subjects is the average of your GPA ranks in the four - including any fails.