The short answer
Yes — raspberries are a safe, antioxidant-rich treat.
Why
Raspberries are full of antioxidants and vitamin C, and the whole berry is fine to eat. They're sugary, so they stay a treat rather than a daily food.
How to feed it
Wash and offer one whole or lightly mashed. They may stain the beak (harmless).
How much & how often
One or two, a few times a week.