CREATE FUNCTION [dbo].[CheckLocation]
(
    @locationId Int
)
RETURNS bit
AS
BEGIN
    //code
END

<Function Name="CheckLocation" ReturnType="bit" Aggregate="false" BuiltIn="false" NiladicFunction="false" IsComposable="true" ParameterTypeSemantics="AllowImplicitConversion" Schema="dbo" >
<Parameter Name="locationId" Type="int" Mode="In" />
</Function>

public partial class MainModelContainer
{
    [EdmFunction("MainModel.Store", "CheckLocation")]
    public bool CheckLocation(int locationId)
    {
        throw new NotSupportedException("Direct calls not supported");
    }
}

Context.CheckLocation(locationId);

var students = context.Locations
    .Select ( new  {  location= CheckLocation(locationId)}):