As far as charging freight in the invoice is concerned. We need to find out whether or not the same is taxable ? Lets examine.
Charging freight in the invoice is amounts to 'Services by way of transportation of goods" which is exempt and covered under the list of exempted services at serial number 9, except in the case of (a) services of GTA or (b) services of Courier Agency.
If you are neither covered under the definition of GTA or courier agency, charging freight for "transportation of goods by road" in the invoice is an exempted service provided by you. In fact you are not providing any service, you are just passing through the freight charges of GTA for transportation of goods to your customer.
Once services provided are exempted, you are supposed to charge tax under GST. Neither it will be termed as "Composite supply of goods and Services as the service you are intended to provide is exempt from tax.