Gst rate on freight

Dear Friends,

I am going to make a sale invoice intra state supply.

In 1 invoice I have 2 difference goods and the gst rate is also 5% & 12%.

We all know that gst is applicable on freight. But my question is in 1 invoice if there is 2 difference rate then how to calculate gst rate on frieght.

My question is:-

1) Gst rate on freight will be 5% or 12% or both or what % should I calculate?

2) wheather there will be any issue for filing gstr 1 if I add 2 difference rate in 1 invoice?