A similar issue is discussed in this KB article: Resolving Touch Responsiveness of TextBoxes in RadPanelBar on iPad.
To resolve this, you can disable the touch scroll extender when the page loads, which should allow the text boxes to respond to touch events as expected. Please try the following JavaScript snippet in your page:
<script>
function OnClientLoad(sender, args) {
if (Telerik.Web.Browser.safari && Telerik.Web.Platform.ios && sender._touchScrollExtender) {
sender._touchScrollExtender.disable();
}
}
</script>
<telerik:RadListBox runat="server" ID="RadListBox1" OnClientLoad="OnClientLoad"></telerik:RadListBox>