Gst on freight charged in the invoice

Relevant Case: Normally companies supply different kinds of goods on a same invoice chargeable with different GST rates. In that case the main issue that arises with the company is where to mention the Freight charges in the invoice-After the taxable value or before the taxable value so that it can be included in the taxable value. Also, if the freight is included in the taxable, at what rate GST would be levied on it as the charges are on a group of supplies containing goods of varied GST rates. It would certainly be impractical to include the freight portion of each good in its assessable value. How the whole invoicing and GST provisions are to be complied in such scenario? Query under consideration: 1) Whether Freight Charges are to be included in the GST Assessable Value? 2) If yes, there are several items in the invoice at what rate GST is to be charged on the freight?