Thank you for writing.
You can use the Orientation property of the IconsListViewElement to control the flow direction of the items in the list view. Here is an example:
.radListView1.ViewType = ListViewType.IconsView;
.radListView1.ListViewElement.ViewElement).Orientation = Orientation.Horizontal;
I hope this will be useful. Should you have further questions, I would be glad to help.
the Telerik team