Thank you for contacting us.
Kendo Editor has no out of the box tools for adding / inserting form elements such as input, select (dropdown) etc.
What you can do is try to implement a custom popup that will insert the desired html. Helpful information and a basic example regarding this matter can be found in the following online help article http://docs.telerik.com/kendo-ui/controls/editors/editor/how-to/insert-html-via-custom-popup-tool.
You can also submit this as a feature request on UserVoice, so that it is considered for implementation in a future release.
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