Hi Steen,
Yes. You can provide all the platform specific font families, please refer the following code snippet,
Code snippet [C#]:
Font font = Device.OnPlatform(
iOS: Font.OfSize ("MarkerFelt-Thin", 18),
Android: Font.OfSize ("Droid Sans Bold", 18),
WinPhone: Font.OfSize ("Courier New", 18)
);
chart.Title = new ChartTitle(){ Text = " Chart Header", Font =font};
Please let us know if you require further assistance on this.
Thanks,
Suresh B.