Hello, this is a tricky concept. The sentence is not used much in the modern English language, if at all. However it often means, 'if there is a chance' and it appears after expressions of scarcity. Example: Roberto hardly ever goes to the gym, if it all. The expression 'if at all' in the above sentence reduces the small chance of Roberto going to the gym to almost zero. Another example: More women are having fewer children, if at all. I hope this helps!