Thermal Bridge heat Transfer

Hi i try to solve thermal bridge example of Featool
https://www.featool.com/doc/heat_transfer_05_thermal_bridge1#tut_ht05

my heat equation with convection and diffusion

problem heat(u,v) =
int2d(Th)( kappa * (dx(u) * dx(v) + dy(u) * dy(v)))   	
 + int1d(Th)(Rs * u * v)
  - int1d(Th)(Rs * Ts * v);

Rs and Ts are function
func Ts =
+ (0.0)(label==Te)
+ (20.0)
(label==Ti)
;

func Rs  =
+ (0.11)*(label==Ti)
+ (0.06)*(label==Te)
;

In the tutorial set label isolated

How-to set label are isolated whith freefem++?

It is very simple , do nothing on this border.