Multisim is a circuit simulation and design software developed by National Instruments (NI). It's widely used in electronics and electrical engineering for designing, simulating, and testing electronic circuits.

RapidFileShare seems to be a file-sharing platform or service, but I couldn't find much information about it. If you're looking for a way to share files, there are many legitimate services available, such as WeTransfer, Dropbox, or Google Drive.