如何在golang中将[] string或[] byte类型传递给SplitAfterN？

I'm reading file line by line and like to split line based on substring. But when I use SplitAfterN with read line passed, I'm facing below error,

cannot convert 'variable' (type []string) to type string

where 'variable' = []string type

package main

import (
    "bufio"
    "flag"
    "fmt"
    "log"
    "os"
    "strings"
)

func main() {
    var fLine []string

    FileName := flag.String("fpath", "Default file path", "File path description ")
    flag.Parse()

    fptr, err := os.Open(*FileName)
    if err != nil {
        log.Fatal(err)
    }

    FileScanner := bufio.NewScanner(fptr)
    for FileScanner.Scan() {
        // Append each line into one buffer while reading
        fLine = append(fLine, FileScanner.Text())
        splitline := strings.SplitAfterN(fLine, "12345", 2)
        fmt.Println("Splited string = ", splitline[1])
    }
}

I'm expecting below line to split passed argument (fLine) splitline := strings.SplitAfterN(fread, "12345", 2)