As simple as can be - so long as you know your dog's weight.
Feed 2-3% of your dog's weight in raw food daily.
For example, if your dog is 20kg.
20 x 2% = 0.4
20 x 3% = 0.6
Therefore, you would feed between 400g and 600g to your dog per day. I would advise starting with 500g (2.5%) and then adjusting accordingly if necessary.
If you don't know your dog's weight, you can take him/her to your veterinary surgery to be weighed for free. If this is not possible for any reason, you will need to estimate their weight and then adjust the amount fed over time, if necessary.