Hi guys, do you know how to add a KLib file to a CMake project ?

you mean to build a klib, or to use it? For example in CURL sample smth along lines of

cmake_minimum_required(VERSION 3.8)

set(CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR}/../../KotlinCMakeModule)

project(CurlHTTP Kotlin)

set(CURL_LIBRARY "-lcurl")
find_package(CURL REQUIRED)

cinterop(
        NAME curl_kt
        DEF_FILE src/c_interop/libcurl.def
        COMPILER_OPTS "-I ${CURL_INCLUDE_DIR}"
)

konanc_executable(
        NAME Curl
        SOURCES src/kotlin/
        LIBRARIES curl_kt
        LINKER_OPTS "${CURL_LIBRARY}"
)

is used

You can take a look for fullstack new project template in CLion in directory clients/webassemply/CMakeLists.txt. It uses prebuilt klibs by command klib(jsinterop ${REPOSITORY}/jsinterop.klib).