Thanks for getting in touch!
You can create a Spline Line Series with one of our SChartLineSeries, however, your would have to provide all the points to curve the line yourself.
This feature has been requested a number of times so we are currently working on an implementation that will automatically add curves to a line series given a set of points. However, this is still in our implementation stage so I am unable to provide any estimate of when this feature will be released.
Let me know if you have any questions.