Define attribute as foreign key ebean intellij

I have the following class:

    @Entity
public class exemplo extends Model {

    @Id
    private Integer id_nome;
    private String Designacao_PT;
    private String Nota_PT;

    public exemplo(Integer id_nome,String Designacao_PT,String Nota_PT){

        this.id_nome= id_nome;
        this.Designacao_PT = Designacao_PT;
        this.Nota_PT = Nota_PT;
    }
}

In this way the primary key is 'id_name'. If I want to put the Designation_PT as a foreign key how can I do it?

I've seen something about @joinColumn but I still have not figured it out. I'm programming in IntelliJ 14.0.2