title: How do you add a footnote if you are using the forestplot R package?
body: <p>Please forgive the naïve question as I am new to R. I have generated a forest plot using a code that I saw and adapted on R bloggers. I would like to add a footnote but I'm not sure how to do it. I've seen different codes but I don't know which one is appropriate. Any advice is much appreciated! Thanks!</p>
  
  <p>The forest plot code is below:</p>
  
  <pre><code>library(ggplot2)
  library(grid)  
  library(gridExtra)   
  library(xtable)
  library(plyr)        
  library(MASS)     
  library(reshape2)
  
  d1 &lt;- read.csv("/view/name_view/vob/folder/subfolder/forestTAF.csv", stringsAsFactors=FALSE)
  
  #Format data so column labels and columns match required graphical output
  subgps &lt;- c(4,5,8,9,12,13,16,17,20,21,24,25,28,29)
  
  #Combine the rest of the columns in the table
  tabletext &lt;- cbind(c("Change due to", d1$Variable), 
                  c("PK Measures", d1$PK.Measures), 
                  c("Recommendation", d1$Recommendation))
  
  #Load forestplot package
  library(forestplot)
  
  #Create forest plot
  png(filename="forestTAF.png",width=1600, height=640)
  forestplot(labeltext=tabletext, graph.pos=3, align=c("l", "c", "l"), 
         mean=c(NA,d1$Point.Estimate), 
         lower=c(NA,d1$Low), upper=c(NA,d1$High),
         title="Drugname \nFold Change and 90% CI",
         xlab="Change Relative to Reference (i.e., without interaction)",
              txt_gp=fpTxtGp(label=gpar(cex=1.25),
                            ticks=gpar(cex=1.1),
                            xlab=gpar(cex = 1.2), 
                            title=gpar(cex = 1.2)),
         col=fpColors(box="black", lines="black"),
         zero=1, cex=0.9, lineheight = "auto", boxsize=0.5, colgap=unit(6,"mm"),
         lwd.ci=2, ci.vertices=TRUE, ci.vertices.height = 0.4)
  </code></pre>