./umk reference SignPDF CLANG -bus

Linking...
Undefined symbols for architecture x86_64:
  "Upp::GetAllFacesSys()", referenced from:
      Upp::Font::FaceList() in Draw$blitz.o
  "Upp::GetFontDataSys(Upp::Font)", referenced from:
      Upp::Font::GetData() const in Draw$blitz.o
  "Upp::GetFontInfoSys(Upp::Font)", referenced from:
      Upp::GetFontInfo(Upp::Font) in Draw$blitz.o
  "Upp::GetGlyphInfoSys(Upp::Font, int)", referenced from:
      Upp::IsNormal(Upp::Font, int) in Draw$blitz.o
      Upp::GetGlyphEntry(Upp::Font, int, unsigned long long) in Draw$blitz.o
  "Upp::RenderCharacterSys(Upp::FontGlyphConsumer&, double, double, int, Upp::Font)", referenced from:
      Upp::Font::Render(Upp::FontGlyphConsumer&, double, double, int) const in Draw$blitz.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)