Define Composite Key and set Foreign Key in Entity Framework 6

I have two class one for sale and second for sale ledger

First TAble

public sale
{
    public int vno  {get;set;}
    public int vtype  {get;set;}
    public string Name {get;set;}
    public string Mobile  {get;set;}
}

I make composite key [vno,vtype] in sale as the primary key

Second Table

public sale
{
    public int vno  {get;set;}
    public int vtype  {get;set;}
    public string ProductName{get;set;}
    public int Qty {get;set;}
    public int Rate{get;set;}
}

There [ vno, vtype ] i want make foreign key from the sale table 

How to achieved this in entity framework 6