Try using a kit like this..........dave..
Silicone Set 
Silicone smoothing rubber tools for all joint shapes
For creating perfect joints fast. Made from a soft rubber like material
An exceptional and unique set of tools of professional results
Set consists of:-
4 mm radius and 45 degree angle tool
7 mm radius and 45 degree angle tool
10 mm radius and 45 degree angle tool
storage case included
First apply your silicone in the normal way. Spray the whole area with a strong soapy solution (i.e. washing up liquid and water, (spray bottle available below) then use these tools to even up and form a perfect joint in seconds! Keeps silicone off your hands