How much fat can you eat on your daily calories?

You should consume at least 0.75g of protein per kg body weight.
After calculating the amounts of calories you get form the recommended intake of protein you subtract that from your daily caloric need. The number you now have should be divided by 9 and you have the amount of fat (in grams) that you should eat to reach your caloric need.

Because carbohydrates are non-essential I did not include them. The lowest amount of fat you should consume is 1g per kg body weight. So if you want to consume carbohydrates you could easily add them into the equation.