SF_11.0, SF_11.1, SF_11.2, SF_12.0, SF_12.1, SF_12.2, SF_13.0, SF_13.1, SF_13.2, SF_13.3, SF_14.0, SF_14.1, SF_14.2, SF_14.3 - https://docs.sitefinity.com/feather-feed-selector

DesignerView.Multi.cshtml

<sf-list-selector sf-feed-selector sf-multiselect="true" sf-sortable="true"
                                sf-provider="properties.ProviderName.PropertyValue"
                                sf-selected-ids="properties.SelectedItemIds.PropertyValue" 
                                sf-selected-items="properties.SelectedItems.PropertyValue"></sf-list-selector>