In case you are asking about dynamic resizing, this is possible as well.
<p>
Set the Splitter width here (@Min.ToString() - @Max.ToString()):
<TelerikNumericTextBoxMin="@Min"Max="@Max"Decimals="0" @bind-Value="@SpliterWidth" />
</p>
<TelerikSplitterOrientation="SplitterOrientation.Horizontal"Height="200px"Width="@( Math.Max(SpliterWidth, Min) + "px" )"><SplitterPanes><SplitterPaneCollapsible="true">
Pane 1
</SplitterPane><SplitterPaneCollapsible="true">
Pane 2
</SplitterPane></SplitterPanes></TelerikSplitter>
@code {
int SpliterWidth = 400;
int Min = 100;
int Max = 1000;
}