warning message when generating pptx file with reporters

[Luis Antonio Cano Perez]

Hi everyone,

I am getting the next warning messages when generating pptx file with reporters:

Warning: System font `Calibri` not found. Closest match: `DejaVu Sans`
Warning: System font `Times New Roman` not found. Closest match: `TeX Gyre Termes`
Warning: System font `Courier New` not found. Closest match: `TeX Gyre Cursor`
Warning: System font `Symbol` not found. Closest match: `DejaVu Sans`

This is my code:

     informe_ob <- pptx(template = 'plantilla_reporte_ejecutivo_ob.pptx')
      informe_ob <- addSlide(informe_ob,"layout_informe_ob")
      slide.layouts(informe_ob)
      slide.layouts(informe_ob, "layout_informe_ob")
      informe_ob <- addPlot(informe_ob, function( ) print(p1()), vector.graphic = TRUE)
      informe_ob <- addPlot(informe_ob, function( ) print(p2()), vector.graphic = TRUE)
      informe_ob <- addFlexTable( informe_ob, flextable = flex_table_ob())
      informe_ob <- addParagraph(informe_ob,as.character(today))
      informe_ob <- addParagraph(informe_ob,as.character(fecha_titulos))
      informe_ob <- addParagraph(informe_ob,as.character(tabla_ob()))
      informe_ob <- addFlexTable( informe_ob, flextable = flex_entorno())
      informe_ob <- addFlexTable( informe_ob, flextable = flex_colectora())
      writeDoc(informe_ob, paste("Reporte_Ejecutivo_",tabla_ob(),"_",fecha_nombre_informe,".pptx",sep = ""))

What is the problem?? How can I solve it??

Thank you in advance.