The current stable version of Xamarin.Forms, 220.127.116.11 supports the Margin property. It accepts a "Thickness" object which specifies the left, top, right and bottom sizes you want.
In XAML, the standard value converter is applied, which means you can specify Margin as one of these:
- "10,20,30,40" - all the sides specifeid in order left, top, right, bottom
- "10,20" - 10 units applied to left and right, 20 to top and bottom. Same as "10,20,10,20"
- "10" - margin of 10 units is applied to all sides, same as "10,10,10,10"
More documentation is available here Margins and Padding