This feature is not supported by RadSpreadProcessing. We have already a request in our backlog and you could vote for its implementation or track its overall progress by subscribing to the related public item
in the feedback portal.
Do you want to have your say when we set our development plans? Do you want to know when a feature you care about is added or when a bug fixed? Explore the Telerik Feedback Portal
and vote to affect the priority of the items