how to add Rectangle shape

Hi Manimaran26312852vdy7,

Thank you for reaching out, and sorry about the delay in response. 

If you refer to adding the rectangle shape provided under the draw, the option is unavailable on the Acrobat Online version. There are limited tools available on the Acrobat Online account for comment. 

For more information on adding comments, refer to the following help document: https://helpx.adobe.com/acrobat/using/commenting-pdfs.html. 

Let us know if you need any help.

Thanks,

Meenakshi