RelativeLayout in XAML - RelativeToView (parent,sibling) => sibling.Bounds.Bottom in Xaml?

Hi guys,

Im trying to set a Constraint in XAML to bottom of another view, in XAML. Normally in C# I would write:
RelativeLayout in XAML - RelativeToView (parent,sibling) => sibling.Bounds.Bottom

How to do it in XAML?
RelativeLayout.YConstraint="{ConstraintExpression Type=RelativeToView,Property=Height, ElementName=logo,Constant=0}"

I tried to set the Property=Height to Property=Bounds.Bottom and Property=Bottom non of them available.

Any suggestions?

Thanks in advance