Facebook Login button with Facebook SDK component

I'm trying to create Facebook login button, I installed Facebook SDK from here http://components.xamarin.com/view/facebook-sdk Now I can't find out how to display the login button, I tried to use

<com.facebook.widget.LoginButton
        android:id="@+id/authButton"
        android:layout_marginTop="8dp"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content" />

but app crashes with "Error inflating class com.facebook.widget.LoginButton"

I can't find any source of information on using this component for Android...