I want to put the pop-up box in the lower third

[li]

<telerikPrimitives:RadPopup.Popup>
                <telerikPrimitives:RadPopup x:Name="popuptwo" IsModal="True" Placement="Center">
                    <telerikPrimitives:RadBorder WidthRequest="250" HorizontalOptions="Center" VerticalOptions="Center" CornerRadius="8" BackgroundColor="White">
                        <Grid>
                            <Grid.RowDefinitions>
                                <RowDefinition Height="42"/>
                            </Grid.RowDefinitions>
                            <Grid.ColumnDefinitions>
                                <ColumnDefinition Width="50*"></ColumnDefinition>
                                <ColumnDefinition Width="50*"></ColumnDefinition>
                            </Grid.ColumnDefinitions>
                            <Grid Grid.Row="0" Grid.ColumnSpan="2">
                                <telerikInput:RadButton ContentLayout="Left,4" x:Name="images" HorizontalOptions="Start"
                                    BorderColor="#c9c9c9" BackgroundColor="#4295F4" TextColor="White" BorderWidth="1" CornerRadius="8"  WidthRequest="400" VerticalOptions="Center"/>
                            </Grid>
                        </Grid>
                    </telerikPrimitives:RadBorder>
                </telerikPrimitives:RadPopup>
            </telerikPrimitives:RadPopup.Popup>

[Didi]

Hi,

The popup position depend on its Placement. It is related to the placement target, placement and horizontal and vertical offsets. More details can be found here: https://docs.telerik.com/devtools/xamarin/controls/popup/popup-key-features#placement-configuration - example provided in the article

It is up to you how to position the popup. You can also apply the HorizontalOffset and VerticalOffset properties to specify the distance between the popup placement target and the alignment point. 

Regards,
Didi
Progress Telerik