hc_annotations example

library(highcharter)
highchart() %>%
    hc_chart(renderTo="container") %>%
    hc_series(list(data=c(29.9, 71.5, 106.4, 129.2, 144.0, 176.0))) %>%
    hc_annotations(list(xValue=4, yValue=125, title=list(text="Annot")))

library(highcharter)
highchart() %>%
    # hc_chart(renderTo="container") %>%
    hc_series(list(data=c(29.9, 71.5, 106.4, 129.2, 144.0, 176.0))) %>%
    hc_annotations(list(xValue=4, yValue=125, title=list(text="Annot")))