RadCalendar uses the ASP.NET Calendar week numbering. You have a couple of options to customize this numbering, but I am afraid you can't define completely custom oen such as first week starting in February. Sorry about the inconvenience.
All the best,
the Telerik team
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?
Telerik Public Issue Tracking
system and vote to affect the priority of the items