How much to feed my dog

I have a Jack Chi dog.

Her ideal weight is 6kg - her last vet weight check (Sept) was 5.2kg.

I currently feed her James Wellbeing Grain free (100g split between two meals) but am planning on gradually changing to the Original Akela in Medium. 

We go for 2 30 minutes walks a day. 

How much should I feed her?