Does anyone know of a whistle sound in either Dim Pro or Rapture? I have had a look and nothing obvious jumps out, so I was wondering if there is one and it is called another name?
 
thx
 

A whistle could be a lot of things. Not sure if this is the whistle you are interested it, there are whistle samples used in DimPro DSF E-MU Proteus Examples "Mo' Phatt > Mo Dist.prog" and "PX-7 > Hightboy).prog"
 
I would look at http://www.freesound.org/browse for whistle samples and load them into DimPro or Rapture
 

I would also suggest you look in percussion kits in something like Battery 3 or whatever drum synths you use.  Those frequently will have a whistle.
 
Bob Bone
 

Check out https://www.freesound.org/
 

Cool, thanks guys. I had not heard of the freesound site before

Okay I found some at that site, but how do I use them to create a melody line????

For that you will need a sampler.
 
If you have Kontakt, you can use that (if you don't, why not?) 
Seriously, if you don't have it, then you can try using DropZone, the Sonar "sampler".
Or there are a few free ones out there, like HighLife sampler.  Or UVI Workstation.
 
You can also attempt to manually transpose the samples as well, but it's much easier and flexible using a sampler.
 

The simplest way would be to drop the sample into a DimPro or Rapture element. If you want to use more than one sample, an sfz file will let you map the samples to different parts of the keyboard. You could even use the different pads in Session Drummer for different samples.
 
Another free sampler http://www.tx16wx.com/

Okay thanks guys - so I need to create a sample first okay got it. I might just try whistling the line myself , might be quicker and easier (for someone who has never used sampling before

When I read your post at first, it did not emphasize whether you wanted a simple bird whistle, human whistle for sporting event or chick call (sexist), a train whistle.....................But, you need to whistle a melody?  
If you got Kontakt, then this one sounds pretty interesting
http://realitone.com/realiwhistle