diff --git a/doc/.DS_Store b/doc/.DS_Store
new file mode 100644
index 0000000000000000000000000000000000000000..3f97eb09919316914295899ad5e3ac3273c835fc
Binary files /dev/null and b/doc/.DS_Store differ
diff --git a/doc/sdk-configuration.md b/doc/sdk-configuration.md
index d8c792faa991a8a085f89859e5ee19879d3149cc..7d375f91cf2238f60b0a825779b5f4637a70fe7e 100644
--- a/doc/sdk-configuration.md
+++ b/doc/sdk-configuration.md
@@ -27,7 +27,7 @@ This file could also be fullfilled by [enviroment variables](../samples/envirome
 
 - capif_callback_url:The Url you want to recieve CAPIF notifications(This functionality is not currently available) 
 
-- csr fields: Seven information fields for generating your invoker certificate 
+- csr fields: Seven information fields for generating your invoker certificate(csr_country_name must be only two letters) 
 
 - capif_username: CAPIF username