Thanks for your interest on our products.
For Smartwatch applications we recommend the Ultra Low Voltage Intel Quark SoC processors: https://communities.intel.com/servlet/JiveServlet/previewBody/21829-102-2-25121/Intel%20Quark%20ProductBrief_001.pdf Intel® Quark SoC X1000
We also offer the Intel Curie module, a kit powered by Quark processors that help developers to test their platforms. It includes a RTOS: http://download.intel.com/newsroom/kits/ces/2015/pdfs/Intel_CURIE_Module_Factsheet.pdf Intel® Curie Module Fact Sheet
Hope this information is useful for you.