Rice milk is fine, as long as it’s unsweetened. Treat it as you would any plant-based milk. Keep in mind rice milk and almond milk are both very low in protein, so you may want to split your protein between plant-based milk and nuts or seeds.
8 oz. rice milk (or any plant-based milk) = 1 protein serving for both women and men
If splitting your protein, have 4 oz. rice or almond milk and 1 oz. nuts or seeds.