You can find someones profile by clicking on the first letter of their username then selecting their name from the list

A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Results

fabrics
fade2dust
Faith5by5
fatmat
fattymatty
Ferodo
Ferretgirl
FFB
Fish
fishie
fishy
FiveByFive
FlamingJune
flippin 'ell
Fluffy Bunny
forumgawd
foulksey
FrancisDavey
FRANK
Freakzilla
Fred
frog
Funky Monkey
Fun_in_a_pill
Furyan_Babe