RadScheduleView does not have built-in zooming on the orientation different than the timeruler. However it has different properties that can be used to fit your needs, but we need more details before providing you with suggestions. That is why Is it possible to give us more details on what you men by horizontal zoom -
Do you need to change the count of displayed days? - you can do this by changing the VisibleDays
property of the view definition depending on the slider value.(Also, could you specify which view definition do you use?)
Do you need to change the width? - you can try setting the width of the control depending on the slider value.
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