diff --git a/.readthedocs.yaml b/.readthedocs.yaml
index 921fded..ebe43f8 100644
--- a/.readthedocs.yaml
+++ b/.readthedocs.yaml
@@ -15,6 +15,9 @@ sphinx:
   configuration: docs/source/conf.py
 
 
+formats:
+  - pdf
+  - epub
 # Optionally set the version of Python and requirements required to build your docs
 
 python:
diff --git a/examples/loadOptics_example.py b/examples/loadOptics_example.py
new file mode 100755
index 0000000..520fc5a
--- /dev/null
+++ b/examples/loadOptics_example.py
@@ -0,0 +1,5 @@
+from exosim.tasks.load import LoadOpticalElement
+
+
+class LoadOpticalElementDefault(LoadOpticalElement):
+    pass