To check size used by data and indexes You can use following script

If anyone is interested in how to list columns in the main key on the mssql server then I present a quick script.

SELECT
    Col.Column_Name
    ,Col.Table_Name
    ,OBJECT_ID(Col.Table_Name) AS [object_id]
FROM
    INFORMATION_SCHEMA.TABLE_CONSTRAINTS Tab
    ,INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE Col
WHERE
    Col.Constraint_Name = Tab.Constraint_Name
    AND Col.Table_Name = Tab.Table_Name
    AND Constraint_Type = 'PRIMARY KEY'
    AND [Col].Table_name='<TABLENAME>'