diff --git a/app.yaml.sample b/app.yaml.sample
index 7e1e0bd..c617b97 100644
--- a/app.yaml.sample
+++ b/app.yaml.sample
@@ -18,4 +18,5 @@ env_variables:
   CONTACT_REPLY_EMAIL: "noreply@example.com"
   CONTACT_REPLY_BCC_EMAIL: "contact@example.com"
   DEMO_URL: "https://demo.example.com/"
-  ALLOWED_ORIGINS: "127.0.0.1,example.com"
\ No newline at end of file
+  ALLOWED_ORIGINS: "127.0.0.1,example.com"
+  RECAPTCHA_PRIVATE_KEY: "value-of-recaptcha-private-key"
\ No newline at end of file