如何在主题：“框”下的rmarkdown投影仪幻灯片上添加页码？

如何解决如何在主题：“框”下的rmarkdown投影仪幻灯片上添加页码？

我使用rmarkdown投影仪，尝试在每张幻灯片的底部添加幻灯片编号，但一直失败。无论如何，我可以在称为“框”的投影仪主题下在每页上添加幻灯片编号吗？

---
title: "Big Business" 
author: |
| Mr. Bean
| Sunny College
output: 
beamer_presentation:
    theme: "Boxes"
    citation_package: natbib
biblio-style: apalike 
incremental: TRUE
header-includes:
- \usepackage{makecell}
- \usepackage{booktabs}
- \usepackage{adjustBox}
---
# Motivation
Big business

# Motivation 2
Small business 

解决方法

boxes主题具有特殊的语法，可以将内容添加到脚注中：

 \addfootbox{normal text}{\hfill\insertframenumber\quad}

（用您喜欢的任何其他投影机颜色替换<normal text>

MWE：

---
title: "Big Business" 
author: |
  | Mr. Bean
  | Sunny College
output: 
  beamer_presentation:
    theme: "boxes"
    citation_package: natbib
biblio-style: apalike 
incremental: TRUE
header-includes:
  - \usepackage{makecell}
  - \usepackage{booktabs}
  - \usepackage{adjustbox}
  - \addfootbox{normal text}{\hfill\insertframenumber\quad}
---

# Motivation
Big business

# Motivation 2
Small business