diff --git a/NAMESPACE b/NAMESPACE
index f0de41ae801dac26eeb3c65d8c36b72cf8d5c6de..4e5a585204d5cb91aa55345376882a962b534d3b 100644
--- a/NAMESPACE
+++ b/NAMESPACE
@@ -62,6 +62,7 @@ export(prj_relative_permeability)
 export(prj_search_length_algorithm)
 export(prj_solution)
 export(prj_source_term)
+export(prj_surface)
 export(prj_time_loop)
 export(prj_time_stepping)
 export(prj_tl_process)
diff --git a/man/prj_surface.Rd b/man/prj_surface.Rd
new file mode 100644
index 0000000000000000000000000000000000000000..87598f133c49b5e50c2d4ecb1d05fbf3028c09ca
--- /dev/null
+++ b/man/prj_surface.Rd
@@ -0,0 +1,16 @@
+% Generated by roxygen2: do not edit by hand
+% Please edit documentation in R/prj_chemical_system.R
+\name{prj_surface}
+\alias{prj_surface}
+\title{prj_surface}
+\usage{
+prj_surface(site_unit = NULL, ...)
+}
+\arguments{
+\item{site_unit}{Optional: string}
+
+\item{...}{site}
+}
+\description{
+tag: surface
+}