Look here to see how Paul suggests you can use DSD+
viewtopic.php?t=142
regarding antennas, I'm not sure what frequencies you are considering but I imagine VHF/UHF. The Discone antenna is pretty popular - available in the US from Ham Radio Outlet for example or in the UK Waters and Stanton - these typically give unidirectional broadband coverage from 25MHz up to either 1.3GHz or even 2GHz.... the cheaper variety are receive only. Some come with coax. They do take up quite a bit of room. Make sure you terminate the coax with a male SMA plug for plugging into the RSP antenna socket. (or get the appropriate adapter)
For a smaller antenna solution (window sill) and say if you mainly use it on a couple of bands, then a quarter wave whip antenna with a simple ground-plane will work quite well close to an upstairs window. An alternative is a simple half wave dipole (inner coax to one 1/4 wave stub and the outer of the coax connected to another quarter wave stub - each stub can be normal copper bell-wire or household mains flex). Even wire taped to a window can be very effective. To work out the size, a look here for a handy calculator
http://www.csgnetwork.com/antennageneri ... ncalc.html
Best regards, Jon