Si4010 is not on the device selection list when you try to create a new project from Silabs IDE. This looks like Si4010 is not supported by the IDE.
The Silabs IDE does support the Si4010, but doesn't contain the necessary header files to generate an Si4010 project automatically. Instead you should start from an Si4010 example project like keyfob_demo_2 and modify it according to your needs. The IDE supports downloading and debugging code to the Si4010 and can display content of special Si4010 SFRs and system variables in the View->Debug Windows menu. For details see chapter 4 of AN370 and chapter 36 of the Si4010 datasheet.
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AN 370 refers to a list of required files which are supposed to reside in in a directory called common\src.
Where may I find these files and this directory!? I can't compile my project.