MainPage.xaml

<ContentPage xmlns:telerikPrimitives="clr-namespace:Telerik.XamarinForms.Primitives;assembly=Telerik.XamarinForms.Primitives"
             xmlns:telerikInput="clr-namespace:Telerik.XamarinForms.Input;assembly=Telerik.XamarinForms.Input"
             Title="Contoso">
    <ContentPage.ToolbarItems>
        <ToolbarItem Text="Menu" Clicked="OpenPopup" />
    </ContentPage.ToolbarItems>
    
    <telerikPrimitives:RadPopup.Popup>
        <telerikPrimitives:RadPopup x:Name="popup" IsModal="false" Placement="Right"
                                    VerticalOffset="10" OutsideBackgroundColor="#6F000000">
            <telerikPrimitives:RadBorder CornerRadius="2" 
                                         BackgroundColor="White">
                <Grid Padding="20">
                    <Grid.RowDefinitions>
                        <RowDefinition Height="30" />
                        <RowDefinition Height="20" />
                        <RowDefinition Height="40" />
                    </Grid.RowDefinitions>
                    <Label Text="Please rate your experience" />
                    <telerikInput:RadShapeRating Grid.Row="1" />
                    <Button Grid.Row="2" Padding="2" HorizontalOptions="End" Text="Send" Clicked="ClosePopup" />
                </Grid>
            </telerikPrimitives:RadBorder>
        </telerikPrimitives:RadPopup>
    </telerikPrimitives:RadPopup.Popup>
    
    <StackLayout>
        <!-- Place new controls here -->
    </StackLayout>
</ContentPage>

MainPage.xaml.cs

public partial class MainPage : ContentPage
{
    public MainPage()
    {
        InitializeComponent();
    }

    private void OpenPopup(object sender, EventArgs e)
    {
        popup.IsOpen = true;
    }

    private void ClosePopup(object sender, EventArgs e)
    {
        popup.IsOpen = false;
    }
}

MainPageMultiple.xaml.cs

private void OpenFeedbackMenu(object sender, EventArgs e)
{
    popup.Content = new FeedbackMenu();
    popup.IsOpen = true;
}

private void OpenButtonMenu(object sender, EventArgs e)
{
    popup.Content = new ButtonMenu();
    popup.IsOpen = true;
}